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JUST ADDED · 18 OCTOBER 2026

126 more ways to get it done.

New calculators and utilities across finance, business, home projects, energy, maths and everyday digital work. Each includes a worked example and clear input limits.

Search all 500 tools ↗Explore the finance toolkit ↗Follow the practical guides ↗

Math & statistics

24 new tools

Math & statistics

Real nth root

Real nth root: Solve y^n = x over the real numbers.

Math & statistics

Exponential growth doubling time

Exponential growth doubling time: Doubling time = ln(2) / ln(1 + growth/100), with a strictly positive growth rate.

Math & statistics

Circular sector area

Circular sector area: Sector area = π × radius² × central angle / 360 for angles from zero through 360 degrees.

Math & statistics

Circular arc length

Circular arc length: Arc length = radius × angle in radians = radius × angle in degrees × π/180.

Math & statistics

Ellipse area

Ellipse area: Ellipse area = π × semi-major axis × semi-minor axis.

Math & statistics

Ellipsoid volume

Ellipsoid volume: Ellipsoid volume = (4/3) × π × a × b × c, where a, b and c are the three semi-axes.

Math & statistics

Circular frustum volume

Circular frustum volume: A circular cone frustum has volume πh(R² + Rr + r²)/3.

Math & statistics

Torus volume

Torus volume: For a ring torus, volume = 2π² × major radius × tube radius².

Math & statistics

Distance from a point to a line

Distance from a point to a line: For line ax + by + c = 0, perpendicular distance is |ax₀ + by₀ + c| / √(a² + b²).

Math & statistics

Angle between two 2D vectors

Angle between two 2D vectors: Angle = arccos[(A·B)/(|A||B|)], returned in degrees from 0 to 180.

Math & statistics

Harmonic mean

Harmonic mean: Harmonic mean = count / Σ(1/value).

Math & statistics

Geometric mean

Geometric mean: Compute exp(mean(ln(value))) for positive observations.

Math & statistics

Coefficient of variation

Coefficient of variation: Sample coefficient of variation = sample standard deviation / arithmetic mean × 100.

Math & statistics

Mean absolute deviation about the mean

Mean absolute deviation about the mean: Find the arithmetic mean, then average the absolute distances of observations from that mean.

Math & statistics

Cohen’s d for independent samples

Cohen’s d for independent samples: Cohen’s d = difference of means divided by pooled sample SD; pooled variance weights each sample variance by n−1.

Math & statistics

Probability of at least one success

Probability of at least one success: For independent equal-probability trials, P(at least one success) = 1−(1−p)^n.

Math & statistics

Modular exponentiation

Modular exponentiation: Compute base^exponent mod modulus using exponentiation by squaring with exact BigInt integer arithmetic.

Physics & engineering

24 new tools

Physics & engineering

Ideal projectile horizontal range

Ideal projectile horizontal range: For equal launch and landing heights without drag, horizontal range = v² sin(2θ)/g.

Physics & engineering

Free-fall time from rest

Free-fall time from rest: For a body released from rest with constant gravity and no drag, fall time = √(2h/g).

Physics & engineering

Centripetal force

Centripetal force: The inward force needed for uniform circular motion is F = mv²/r.

Physics & engineering

Torque from force and angle

Torque from force and angle: Torque magnitude = radius × force × |sin(angle between radius and force)|, in newton-metres.

Physics & engineering

Archimedes buoyant force

Archimedes buoyant force: Buoyant force = fluid density × displaced volume × gravitational acceleration, directed upward in a static fluid.

Physics & engineering

Hydrostatic gauge pressure

Hydrostatic gauge pressure: Gauge pressure increase below a static fluid surface is ρgh.

Physics & engineering

Ideal gas pressure

Ideal gas pressure: Ideal gas pressure P = nRT/V, using R = 8.31446261815324 J/(mol·K).

Physics & engineering

Sensible heat energy

Sensible heat energy: Heat energy Q = mass × specific heat capacity × temperature change.

Physics & engineering

Latent heat for a phase change

Latent heat for a phase change: Energy for a phase change at the transition temperature is Q = mass × specific latent heat.

Physics & engineering

Linear thermal expansion

Linear thermal expansion: Change in length ΔL = original length × linear expansion coefficient × temperature change.

Physics & engineering

Steady thermal conduction through a slab

Steady thermal conduction through a slab: Heat transfer rate = conductivity × area × temperature difference / thickness for one-dimensional steady conduction.

Physics & engineering

Carnot thermal efficiency limit

Carnot thermal efficiency limit: Maximum reversible heat-engine efficiency = (1−cold temperature/hot temperature) × 100, with absolute temperatures.

Physics & engineering

Wave propagation speed

Wave propagation speed: Wave speed = frequency × wavelength.

Physics & engineering

Thin lens image distance

Thin lens image distance: For the real-is-positive thin-lens convention, 1/f = 1/object distance + 1/image distance.

Physics & engineering

Sound intensity level

Sound intensity level: Sound intensity level = 10 log₁₀(intensity/reference intensity), in decibels.

Physics & engineering

Combine independent sound levels

Combine independent sound levels: For uncorrelated sources with the same reference, combined level = 10 log₁₀(10^(L₁/10)+10^(L₂/10)).

Physics & engineering

Coulomb electrostatic force

Coulomb electrostatic force: Signed interaction F = k q₁q₂/r² with k ≈ 8.9875517923×10⁹ N·m²/C².

Physics & engineering

Electric field from a point charge

Electric field from a point charge: Radial electric field = kq/r² with k ≈ 8.9875517923×10⁹ N·m²/C².

Physics & engineering

Uniform wire resistance

Uniform wire resistance: Resistance R = resistivity × length / cross-section area, converting mm² to m².

Physics & engineering

Energy stored in an inductor

Energy stored in an inductor: Stored magnetic energy = ½ × inductance × current² for a linear inductor.

Physics & engineering

Ideal transformer secondary voltage

Ideal transformer secondary voltage: Ideal secondary voltage = primary voltage × secondary turns / primary turns.

Unit converters

20 new tools

Unit converters

Torque converter

Torque converter: Convert torque by multiplying the input by its source-unit factor and dividing by its destination-unit factor.

Unit converters

Density converter

Density converter: Convert density by multiplying the input by its source-unit factor and dividing by its destination-unit factor.

Unit converters

Volumetric flow converter

Volumetric flow converter: Convert volumetric flow by multiplying the input by its source-unit factor and dividing by its destination-unit factor.

Unit converters

Dynamic viscosity converter

Dynamic viscosity converter: Convert dynamic viscosity by multiplying the input by its source-unit factor and dividing by its destination-unit factor.

Unit converters

Kinematic viscosity converter

Kinematic viscosity converter: Convert kinematic viscosity by multiplying the input by its source-unit factor and dividing by its destination-unit factor.

Unit converters

Electric charge converter

Electric charge converter: Convert electric charge by multiplying the input by its source-unit factor and dividing by its destination-unit factor.

Unit converters

Capacitance converter

Capacitance converter: Convert capacitance by multiplying the input by its source-unit factor and dividing by its destination-unit factor.

Unit converters

Inductance converter

Inductance converter: Convert inductance by multiplying the input by its source-unit factor and dividing by its destination-unit factor.

Unit converters

Magnetic flux converter

Magnetic flux converter: Convert magnetic flux by multiplying the input by its source-unit factor and dividing by its destination-unit factor.

Unit converters

Magnetic flux density converter

Magnetic flux density converter: Convert magnetic flux density by multiplying the input by its source-unit factor and dividing by its destination-unit factor.

Unit converters

Illuminance converter

Illuminance converter: Convert illuminance by multiplying the input by its source-unit factor and dividing by its destination-unit factor.

Unit converters

Luminance converter

Luminance converter: Convert luminance by multiplying the input by its source-unit factor and dividing by its destination-unit factor.

Unit converters

Radioactivity unit converter

Radioactivity unit converter: Convert radioactivity unit by multiplying the input by its source-unit factor and dividing by its destination-unit factor.

Unit converters

Molar concentration converter

Molar concentration converter: Convert molar concentration by multiplying the input by its source-unit factor and dividing by its destination-unit factor.

Unit converters

Molar mass converter

Molar mass converter: Convert molar mass by multiplying the input by its source-unit factor and dividing by its destination-unit factor.

Unit converters

Specific heat capacity converter

Specific heat capacity converter: Convert specific heat capacity by multiplying the input by its source-unit factor and dividing by its destination-unit factor.

Unit converters

Thermal conductivity converter

Thermal conductivity converter: Convert thermal conductivity by multiplying the input by its source-unit factor and dividing by its destination-unit factor.

Unit converters

Areal mass density converter

Areal mass density converter: Convert areal mass density by multiplying the input by its source-unit factor and dividing by its destination-unit factor.

Unit converters

Textile linear density converter

Textile linear density converter: Convert textile linear density by multiplying the input by its source-unit factor and dividing by its destination-unit factor.

Unit converters

Angular speed converter

Angular speed converter: Convert angular speed by multiplying the input by its source-unit factor and dividing by its destination-unit factor.

Money & borrowing

25 new tools

Money & borrowing

Rule of 72 comparison

Rule of 72 comparison: Approximate doubling years = 72 / annual percentage growth rate.

Money & borrowing

Level perpetuity present value

Level perpetuity present value: Present value of end-of-period level payments continuing forever = payment / discount rate.

Money & borrowing

Growing perpetuity present value

Growing perpetuity present value: Present value = next-period cash flow / (discount rate − growth rate).

Money & borrowing

Annuity due present value

Annuity due present value: Annuity-due present value = payment × [1−(1+r)^−n]/r × (1+r).

Money & borrowing

Periods to reach a savings goal

Periods to reach a savings goal: Solve target = start(1+r)^n + deposit[(1+r)^n−1]/r and round up to the next whole deposit period.

Money & borrowing

Education cost inflation target

Education cost inflation target: Inflate each annual education payment separately from today, then sum the nominal payments across the study years.

Money & borrowing

Retirement income gap

Retirement income gap: Monthly income gap = max(0, desired spending − pension income − other income).

Money & borrowing

Fund switch fee break-even

Fund switch fee break-even: Approximate break-even years = switching cost / annual fee savings on an unchanged balance.

Money & borrowing

Holding-period return after costs

Holding-period return after costs: Holding-period return = (sale proceeds + income − costs − initial investment) / initial investment × 100.

Money & borrowing

Bond Macaulay duration

Bond Macaulay duration: Discount each payment at yield/frequency.

Money & borrowing

Bond modified duration price sensitivity

Bond modified duration price sensitivity: Modified duration = Macaulay duration / (1 + nominal yield/frequency), approximating fractional price sensitivity to yield.

Money & borrowing

Gordon dividend growth valuation

Gordon dividend growth valuation: Model value = last dividend × (1+growth) / (required return − growth), with required return greater than growth.

Money & borrowing

Preferred share current yield

Preferred share current yield: Current yield = annual preferred dividend / current price × 100.

Money & borrowing

Theoretical ex-rights price

Theoretical ex-rights price: TERP = (existing share count × old price + new share count × subscription price) / total share count.

Money & borrowing

Weighted average cost of capital

Weighted average cost of capital: WACC = equity weight × cost of equity + debt weight × cost of debt × (1−tax rate).

Money & borrowing

Debt service coverage ratio

Debt service coverage ratio: Debt service coverage ratio = annual net operating income / annual debt service for the same period.

Money & borrowing

Remaining loan term from payment

Remaining loan term from payment: Remaining months = −ln(1−monthly rate × balance/payment)/ln(1+monthly rate), rounded up; zero rate uses balance/payment.

Money & borrowing

Canadian mortgage semiannual compounding

Canadian mortgage semiannual compounding: Convert semiannual nominal rate j to monthly rate (1+j/2)^(1/6)−1, then apply the standard monthly amortising-payment formula.

Accounting

18 new tools

Accounting

Current ratio

Current ratio: Current ratio = current assets / current liabilities at the same balance-sheet date.

Accounting

Quick ratio

Quick ratio: Quick ratio = (cash + marketable securities + net receivables) / current liabilities.

Accounting

Cash ratio

Cash ratio: Cash ratio = (cash equivalents + readily marketable securities) / current liabilities.

Accounting

Return on average assets

Return on average assets: ROA = net income / average of opening and closing total assets × 100.

Accounting

Return on average equity

Return on average equity: ROE = net income / average opening and closing equity × 100.

Accounting

Return on capital employed

Return on capital employed: ROCE = EBIT / (total assets − current liabilities) × 100, using the selected balance-sheet date.

Accounting

Interest coverage ratio

Interest coverage ratio: Interest coverage = EBIT / interest expense, expressed as times covered.

Accounting

DuPont three-factor ROE

DuPont three-factor ROE: DuPont ROE = net profit margin × asset turnover × equity multiplier.

Accounting

FIFO inventory issue cost

FIFO inventory issue cost: Issue units from the oldest purchase layer first; sum issued units × layer cost, retaining unissued layers in closing inventory.

Accounting

Units-of-production depreciation

Units-of-production depreciation: Period depreciation = (cost − residual value) × period output / estimated lifetime output.

Accounting

Sum-of-years-digits depreciation

Sum-of-years-digits depreciation: Depreciation for year y = (cost−residual) × (life−y+1) / [life(life+1)/2].

Accounting

Margin of safety in sales

Margin of safety in sales: Margin of safety = actual sales − break-even sales; divide by actual sales for the percentage.

Accounting

Degree of operating leverage

Degree of operating leverage: Operating leverage = contribution margin / operating profit = (sales−variable costs)/(sales−variable costs−fixed costs).

Accounting

Absorption manufacturing unit cost

Absorption manufacturing unit cost: Absorption unit cost = direct material + direct labour + variable manufacturing overhead + allocated fixed manufacturing overhead per unit.

Taxes & fees

12 new tools

Taxes & fees

England and Northern Ireland standard SDLT

England and Northern Ireland standard SDLT: Apply standard residential SDLT bands: 0% to £125,000; 2% to £250,000; 5% to £925,000; 10% to £1.5m; 12% above.

Taxes & fees

Scotland standard residential LBTT

Scotland standard residential LBTT: Apply Scottish standard residential LBTT marginal bands: 0% to £145,000; 2% to £250,000; 5% to £325,000; 10% to £750,000; 12% above.

Taxes & fees

Wales main residential Land Transaction Tax

Wales main residential Land Transaction Tax: Apply Welsh main residential LTT marginal bands: 0% to £225,000; 6% to £400,000; 7.5% to £750,000; 10% to £1.5m; 12% above.

Taxes & fees

New Zealand GST output and input balance

New Zealand GST output and input balance: For standard 15% inclusive amounts, output GST = sales × 3/23 and input GST = claimable purchases × 3/23.

Taxes & fees

Japan mixed-rate consumption tax basket

Japan mixed-rate consumption tax basket: Standard consumption tax including local component is 10%; qualifying reduced-rate net supplies use 8%.

Taxes & fees

Switzerland three-rate VAT basket

Switzerland three-rate VAT basket: Sum standard supplies × 8.1%, reduced supplies × 2.6% and qualifying accommodation × 3.8%.

Taxes & fees

US state and local sales tax stack

US state and local sales tax stack: For additive rates on the same taxable base, total sales tax = purchase × (state + county + city + district rates).

Taxes & fees

Custom country or state progressive tax worksheet

Custom country or state progressive tax worksheet: Apply each supplied marginal rate only to the income slice between consecutive cumulative upper bounds, then sum all band taxes.

Taxes & fees

Germany church tax on assessed tax

Germany church tax on assessed tax: Multiply the independently determined church-tax assessment base by the confirmed 8% or 9% rate.

Pay & allowances

3 new tools

Pay & allowances

End-of-service gratuity accrual planner

End-of-service gratuity accrual planner: Accrue basic salary/30 × days per year for each service tier, then apply the entered salary-month cap if positive.

Pay & allowances

Salary sacrifice marginal net cost

Salary sacrifice marginal net cost: Approximate take-home reduction = gross sacrifice × (1−marginal income-tax saving−employee social-contribution saving).

Previous additions

The previous 204 additions for finance, home projects, maths and everyday digital tasks.

Business & selling

A/B conversion difference and z-test

A/B conversion difference and z-test: Compute conversion rates, their difference and a pooled two-proportion z statistic.

Math & statistics

Absolute and relative error

Absolute and relative error with an explained formula, a worked example and checks for invalid or unsupported inputs.

Physics & engineering

AC real, reactive and apparent power

AC real, reactive and apparent power: Apparent power is RMS voltage × RMS current, multiplied by √3 for balanced three phase with line-to-line voltage.

Dates & time

Add hours, minutes and seconds

Add hours, minutes and seconds: Parse each elapsed duration as hours, minutes and optional seconds, sum whole seconds, then normalize into total hours, minutes and seconds.

Dates & time

Add or subtract calendar months

Add or subtract calendar months with editable inputs, an explained method, a worked example and clearly stated output limits.

Electronics & energy

Appliance electricity audit

Appliance electricity audit: Energy per appliance = rated watts × hours/day × quantity × days /1000.

Math & statistics

Arithmetic sequence and sum

Find a term and the sum of the first n terms of a sequence with a constant difference.

Money & borrowing

Balloon loan payment and schedule

Balloon loan payment and schedule: Regular payment = [principal − balloon/(1+r)^n] × r/[1−(1+r)^−n]; at zero rate use (principal−balloon)/n.

Math & statistics

Bayesian binary-classifier posterior

Bayesian binary-classifier posterior: Apply Bayes’ theorem: posterior after a positive result = prior × true-positive rate / [prior × true-positive rate + (1−prior) × false-positive rate].

Math & statistics

Binomial probability

Binomial probability with an explained formula, a worked example and checks for invalid or unsupported inputs.

Web & design

Blend two HEX colors

Blend two HEX colors with editable inputs, an explained method, a worked example and clearly stated output limits.

Money & borrowing

Bond yield to maturity solver

Bond yield to maturity solver: Solve the discounted coupon-plus-face-value equation by bisection over a nominal annual yield from −90% to 1,000%.

Everyday arithmetic

Box packing in six orientations

Box packing in six orientations: For each of six axis-aligned item orientations, multiply the whole-item counts along the three container dimensions; report the best uniform orientation.

Home & construction

Brick wall quantity with mortar joints

Brick wall quantity with mortar joints using clearly labeled inputs, with the formula, a worked example and practical limits explained.

Business & selling

Business cash runway

Estimate how many months your business cash lasts at a constant monthly net burn rate.

Text & writing

Caesar cipher and ROT13

Caesar cipher and ROT13 locally in your browser, with clear input requirements, a worked example and an explanation of the result.

Dates & time

Calendar date to ISO ordinal date

Calendar date to ISO ordinal date with editable inputs, an explained method, a worked example and clearly stated output limits.

Business & selling

Cash conversion cycle

Cash conversion cycle: enter your own figures, see the result and calculation method, and check the model’s assumptions.

Web & design

Color palette from a HEX color

Generate complementary, analogous, triadic or split-complementary HEX colors by rotating the hue of a base color.

Money & borrowing

Compare three investment return scenarios

Compare three investment return scenarios: For each entered nominal annual return, apply rate/12 monthly before adding the end-of-month contribution.

Money & borrowing

Compare two loan offers

Compare two loan offers: Amortize both offers with rounded monthly interest and a final balance adjustment; compare all payments plus upfront fees.

Math & statistics

Complex number arithmetic

Complex number arithmetic: Use componentwise addition/subtraction, (a+bi)(c+di)=(ac−bd)+(ad+bc)i, and multiply by the divisor’s conjugate for division.

Math & statistics

Covariance of paired data

Covariance of paired data with an explained formula, a worked example and checks for invalid or unsupported inputs.

Developer & data

CRC-32 text checksum

Calculate the standard reflected CRC-32 checksum of the exact UTF-8 bytes of text you enter.

Money & borrowing

Credit card balance transfer comparison

Credit card balance transfer comparison: Compare monthly rounded-interest payoff under the original rate with a transferred balance including the percentage fee, promo months and a later rate.

Money & borrowing

Credit card payoff time

Estimate the time and interest needed to clear a credit card with fixed monthly repayments and no new spending.

Money & borrowing

Credit utilization ratio

Calculate the share of available revolving credit currently used by your entered balances.

Web & design

CSS border-radius generator

CSS border-radius generator with editable inputs, an explained method, a worked example and clearly stated output limits.

Web & design

CSS box-shadow generator

CSS box-shadow generator with editable inputs, an explained method, a worked example and clearly stated output limits.

Developer & data

CSV pivot by group and sum

CSV pivot by group and sum: Group exact cell strings and sum the selected numeric column with decimal arithmetic.

Developer & data

CSV to Markdown table

CSV to Markdown table locally in your browser, with clear input requirements, a worked example and an explanation of the result.

Business & selling

Customer acquisition cost (CAC)

Calculate acquisition cost per new customer from the sales and marketing spending for a consistent period.

Dates & time

Day of the week for a date

Find the weekday name, day number in the year and leap-year status of a Gregorian calendar date.

Electronics & energy

DC two-wire voltage drop

Calculate resistive voltage drop and wire power loss for a two-conductor DC circuit using entered resistivity.

Money & borrowing

Debt snowball vs avalanche comparison

Debt snowball vs avalanche comparison: Add monthly rounded interest, pay fixed minimums, then allocate all remaining budget to the smallest remaining balance (snowball) or highest rate (avalanche).

Home & construction

Deck board spacing and count

Deck board spacing and count: Board count = ceil((deck width + target gap)/(board width+gap)); report exact equal gap if all boards can be full width, otherwise estimate the final rip width.

Money & borrowing

Discounted payback period

Discounted payback period: enter your own figures, see the result and calculation method, and check the model’s assumptions.

Money & borrowing

Dividend income and yield planner

Dividend income and yield planner: Annual gross dividend = shares × dividend per payment × payments per year.

Business & selling

Ecommerce contribution per order

Ecommerce contribution per order: Expected contribution = revenue × (1−refund share) − goods − fulfillment − payment fees − refund share × additional loss − advertising cost.

Business & selling

Economic order quantity (EOQ)

Economic order quantity (EOQ): enter your own figures, see the result and calculation method, and check the model’s assumptions.

Money & borrowing

Equivalent annual cost (EAC)

Equivalent annual cost (EAC): enter your own figures, see the result and calculation method, and check the model’s assumptions.

Electronics & energy

EV charging time and cost

Estimate charging energy, time and electricity cost using battery capacity, charge levels and average wall power.

Math & statistics

Exact fraction arithmetic

Exact fraction arithmetic: Parse signed integer fractions with BigInt, apply the selected operation, normalize the denominator sign and reduce by the greatest common divisor.

Money & borrowing

Extra loan payment savings

Compare payoff time and interest with and without an additional monthly loan payment.

Developer & data

Extract a column from CSV

Extract one CSV column as a JSON array, with an optional spreadsheet-safe one-column CSV download.

Developer & data

Extract email-like addresses and web URLs

Extract email-like addresses and web URLs: Find conservative email-like ASCII tokens or HTTP(S) URL tokens, remove duplicates and return the first occurrence order.

Home & construction

Fence panels and posts

Plan panel and post counts for an open fence run or a closed loop, plus a basic materials budget.

Developer & data

Filter a JSON object array

Filter a JSON object array: Parse the match as a JSON scalar, then keep objects whose own named property is exactly equal in both type and value.

Developer & data

Filter CSV rows by a column

Filter CSV rows by a column: Parse CSV and retain rows whose selected cell equals, contains, or differs from the entered case-sensitive text.

Developer & data

Find and replace within a CSV column

Find and replace within a CSV column: Parse CSV, replace every exact case-sensitive occurrence in the selected column only, and serialize valid CSV.

Developer & data

Find duplicate CSV keys

Find duplicate CSV keys: Build exact composite keys from the selected cells.

Dates & time

Fiscal quarter and date boundaries

Fiscal quarter and date boundaries: Offset the calendar month from the fiscal starting month, take the zero-based quarter, then find the first and last calendar dates in that three-month block.

Money & borrowing

Fixed-coupon bond price

Value a fixed-coupon bond by discounting its remaining coupons and maturity payment at an entered yield.

Developer & data

Flatten JSON to pointer entries

Flatten JSON to pointer entries locally in your browser, with clear input requirements, a worked example and an explanation of the result.

Web & design

Fluid font-size CSS clamp generator

Fluid font-size CSS clamp generator with editable inputs, an explained method, a worked example and clearly stated output limits.

Physics & engineering

Fluid pressure from liquid head

Fluid pressure from liquid head using clearly labeled inputs, with the formula, a worked example and practical limits explained.

Electronics & energy

Four-band resistor color decoder

Four-band resistor color decoder: Decode the first two bands as decimal digits, apply the third-band multiplier and use the fourth band as percentage tolerance.

Math & statistics

Frequency-table mean and variance

Frequency-table mean and variance: Treat each nonnegative integer frequency as a count of repeated observations.

Math & statistics

GCD and LCM of integers

Find the greatest common divisor and least common multiple of two or more integers, including exact large integers.

Math & statistics

Geometric sequence and sum

Find a term and finite sum of a geometric sequence, including ratio zero, one or negative ratios.

Physics & engineering

Gravitational potential energy

Gravitational potential energy using clearly labeled inputs, with the formula, a worked example and practical limits explained.

Math & statistics

Histogram bin and frequency table

Histogram bin and frequency table: Split the observed range into equal-width bins, using left-inclusive/right-exclusive intervals except that the last bin includes the maximum.

Physics & engineering

Hooke’s law spring force and energy

Hooke’s law spring force and energy: Within the linear elastic range, restoring force = −k × displacement and stored energy = ½ × k × displacement².

Dates & time

Hours to ISO 8601 time duration

Hours to ISO 8601 time duration with editable inputs, an explained method, a worked example and clearly stated output limits.

Money & borrowing

How long will savings last?

Estimate how many month-end withdrawals savings can support under a fixed return and withdrawal amount.

Physics & engineering

Ideal lever effort force

Ideal lever effort force: Balance moments about the pivot: effort force × effort arm = load force × load arm.

Money & borrowing

Inflation and purchasing power

Compare a future price with the purchasing power of a fixed amount under an assumed annual inflation rate.

Money & borrowing

Internal rate of return (IRR)

Internal rate of return (IRR): enter your own figures, see the result and calculation method, and check the model’s assumptions.

Math & statistics

Interpolate values from an XY table

Interpolate values from an XY table: Sort distinct x knots, find the two surrounding knots for each query, and linearly interpolate y between them.

Business & selling

Inventory reorder point

Inventory reorder point: Reorder point = mean daily demand × replenishment lead time + safety stock; round upward to a whole unit.

Business & selling

Invoice aging report

Invoice aging report: Compare each due date with the as-of date.

Business & selling

Invoice payment due date

Invoice payment due date: Add the entered number of calendar days, treating the invoice date as day zero.

Developer & data

IPv4 subnet and CIDR calculator

Find an IPv4 network range, subnet mask, broadcast value and conventional usable host range from a CIDR prefix.

Geometry

Irregular polygon area and perimeter

Irregular polygon area and perimeter: Apply the shoelace formula to ordered vertices and sum edge lengths, including the closing edge.

Developer & data

JSON path and type report

JSON path and type report: Walk the JSON structure, using [] for each array item position, and count observed value types at each structural path.

Developer & data

JSON string escape and unescape

JSON string escape and unescape locally in your browser, with clear input requirements, a worked example and an explanation of the result.

Developer & data

JSON structural diff

Compare JSON values structurally and list added, removed or changed paths without treating key order as a change.

Physics & engineering

Kinetic energy

Kinetic energy using clearly labeled inputs, with the formula, a worked example and practical limits explained.

Physics & engineering

LC resonant frequency

LC resonant frequency: For an ideal lumped LC circuit, resonant frequency = 1 / (2π√(L × C)), with L in henries and C in farads.

Dates & time

Leap year checker and year length

Leap year checker and year length with editable inputs, an explained method, a worked example and clearly stated output limits.

Physics & engineering

Linear momentum

Linear momentum using clearly labeled inputs, with the formula, a worked example and practical limits explained.

Money & borrowing

Loan amortization schedule

See a monthly loan amortization schedule and download principal, interest and balance as a CSV file.

Money & borrowing

Loan recast payment after a lump sum

Loan recast payment after a lump sum: Subtract the lump sum from principal and recalculate the fixed payment over the entered remaining term at the same rate.

Dates & time

Meeting time across world time zones

Meeting time across world time zones: Parse a single instant with an explicit offset, then format that instant in each IANA time zone using the browser’s Intl time-zone database.

Developer & data

Merge CSV tables with matching headers

Merge CSV tables with matching headers: Validate that both parsed header rows match exactly, then append all data rows from the second table to the first.

Business & selling

Mixed-rate sales tax basket

Mixed-rate sales tax basket: For each line calculate net × quantity, round its tax to cents, then sum line net, tax and gross amounts.

Money & borrowing

Modified Dietz investment return

Modified Dietz investment return: Return = (ending − starting − net external flows)/(starting + Σ flow × remaining-days/period-days).

Money & borrowing

Modified internal rate of return (MIRR)

Modified internal rate of return (MIRR): enter your own figures, see the result and calculation method, and check the model’s assumptions.

Dates & time

Monthly recurring date schedule

Monthly recurring date schedule with editable inputs, an explained method, a worked example and clearly stated output limits.

Business & selling

Monthly sales growth scenario

Monthly sales growth scenario: Month one uses the starting units; each later month multiplies the previous units by (1+growth).

Math & statistics

Moving average time-series worksheet

Moving average time-series worksheet: For each input row with enough observations, average that row and its previous window−1 values.

Text & writing

NATO phonetic alphabet translator

NATO phonetic alphabet translator locally in your browser, with clear input requirements, a worked example and an explanation of the result.

Money & borrowing

Net present value (NPV)

Discount future net cash flows and subtract the initial outlay to estimate a project’s net present value.

Text & writing

Number to English words

Number to English words: Split the integer into three-digit groups through quadrillions, spell each group in English, and read fractional digits individually after “point”.

Money & borrowing

One-time loan overpayment schedule

One-time loan overpayment schedule: Calculate the normal fixed payment, then apply one extra principal payment after the regular payment in the chosen month.

Math & statistics

Percentile with linear interpolation

Percentile with linear interpolation with an explained formula, a worked example and checks for invalid or unsupported inputs.

Physics & engineering

Pipe flow velocity

Pipe flow velocity using clearly labeled inputs, with the formula, a worked example and practical limits explained.

Physics & engineering

Pipe internal capacity

Pipe internal capacity: Treat the internal bore as a cylinder: volume = π × (internal diameter / 2)² × length.

Physics & engineering

Pipe Reynolds number

Pipe Reynolds number using clearly labeled inputs, with the formula, a worked example and practical limits explained.

Web & design

Pixels and rem converter

Pixels and rem converter with editable inputs, an explained method, a worked example and clearly stated output limits.

Home & construction

Plant spacing grid count

Plant spacing grid count: Place plant centers half a spacing from each boundary.

Math & statistics

Poisson event probability

Poisson event probability with an explained formula, a worked example and checks for invalid or unsupported inputs.

Math & statistics

Polynomial definite integral by Simpson’s rule

Polynomial definite integral by Simpson’s rule: Composite Simpson’s rule: h/3 × [f(a)+f(b)+4Σ odd interior samples+2Σ even interior samples], evaluating the entered polynomial with Horner’s method.

Home & construction

Pool and tank filling time

Pool and tank filling time using clearly labeled inputs, with the formula, a worked example and practical limits explained.

Home & construction

Premixed concrete bag quantity

Premixed concrete bag quantity: Bags = ceil(required m³ × 1000 × (1+waste fraction) / stated litres of wet yield per bag).

Money & borrowing

Present value of an annuity

Present value of an annuity: enter your own figures, see the result and calculation method, and check the model’s assumptions.

Math & statistics

Prime factorization

Decompose a positive whole number into prime factors, exponents and the number of positive divisors.

Money & borrowing

Profitability index

Profitability index: enter your own figures, see the result and calculation method, and check the model’s assumptions.

Home & construction

Rainwater collection worksheet

Rainwater collection worksheet: Harvested litres = rainfall mm × roof catchment m² × efficiency fraction; one mm over one m² equals one litre.

Electronics & energy

RC time constant and settling time

RC time constant and settling time using clearly labeled inputs, with the formula, a worked example and practical limits explained.

Money & borrowing

Real return after inflation

Adjust a nominal return for inflation over the same period to estimate the change in purchasing power.

Business & selling

Reconcile two ledgers by reference

Reconcile two ledgers by reference: Aggregate signed amounts by exact reference on each side; list each reference with its two totals and difference.

Developer & data

Redact selected JSON fields

Redact selected JSON fields: Parse JSON, validate all pointers against the original document, then replace each selected value with the string [REDACTED].

Money & borrowing

Refinance fee break-even

Refinance fee break-even: New payment uses the fixed-rate annuity formula.

Geometry

Regular polygon dimensions

Regular polygon dimensions: For a regular n-sided polygon, apothem = side / (2 tan(π/n)), perimeter = n × side, and area = perimeter × apothem / 2.

Developer & data

Remove duplicate CSV rows

Remove duplicate CSV rows locally in your browser, with clear input requirements, a worked example and an explanation of the result.

Money & borrowing

Rental cash-on-cash return

Rental cash-on-cash return: Annual cash flow = collected rent − operating costs − financing payments.

Money & borrowing

Rental property capitalization rate

Rental property capitalization rate: enter your own figures, see the result and calculation method, and check the model’s assumptions.

Home & construction

Roof pitch and slope angle

Convert measured roof rise and horizontal run into an angle, slope percentage and an x-in-12 roof pitch.

Math & statistics

Root mean square (RMS)

Root mean square (RMS) with an explained formula, a worked example and checks for invalid or unsupported inputs.

Business & selling

Safety stock with fixed lead time

Safety stock with fixed lead time: Safety stock = z × daily demand standard deviation × √lead-time days, rounded upward.

Business & selling

Sales-mix break-even batches

Sales-mix break-even batches: Contribution per mix batch = Σ mix quantity × (selling price − variable cost).

Money & borrowing

Savings with monthly contributions

Project a savings balance from an initial deposit and recurring monthly contributions, with interest and timing shown.

Electronics & energy

Series and parallel resistor network

Series and parallel resistor network using clearly labeled inputs, with the formula, a worked example and practical limits explained.

Math & statistics

Simple linear regression

Simple linear regression with an explained formula, a worked example and checks for invalid or unsupported inputs.

Math & statistics

Solve a linear equation system

Solve a linear equation system: Apply Gaussian elimination with partial pivoting to an n×(n+1) augmented matrix.

Dates & time

Sort dates and inspect calendar gaps

Sort dates and inspect calendar gaps: Validate Gregorian dates, sort them chronologically, preserve duplicates, and report days since the previous sorted date.

Developer & data

Sort JSON object keys

Sort JSON object keys locally in your browser, with clear input requirements, a worked example and an explanation of the result.

Math & statistics

Spearman rank correlation with ties

Spearman rank correlation with ties: Rank each series with average ranks for ties, then calculate Pearson correlation between the two rank series.

Home & construction

Stair riser and run planner

Estimate an equal-riser stair layout from total rise, a chosen maximum riser and horizontal going.

Home & construction

Stock length cutting plan

Stock length cutting plan: Expand requested quantities, sort pieces longest first, and place each in the first existing stock that fits.

Digital quantities

Streaming internet data usage

Estimate streaming data consumption from an average bitrate, daily usage, days and simultaneous devices.

Developer & data

Summarize a numeric CSV column

Summarize a numeric CSV column: Parse nonblank selected cells as numbers; calculate count, sum, mean, minimum and maximum using decimal arithmetic.

Math & statistics

Survey sample size for a proportion

Plan a survey sample size for a proportion from a confidence level, absolute margin and optional population correction.

Business & selling

Tiered marginal commission plan

Tiered marginal commission plan: Apply each rate only to the sales slice inside that cumulative band.

Money & borrowing

Time-weighted investment return

Time-weighted investment return: Compute each subperiod return as end/start −1 and geometrically link the factors.

Money & borrowing

Tip and split the bill

Calculate a tip and split the final bill equally, with a cent allocation that adds up to the total.

Developer & data

Transpose CSV rows and columns

Transpose CSV rows and columns: Treat every CSV row as data and swap row/column indices: output[j][i]=input[i][j].

Developer & data

TSV and CSV converter

TSV and CSV converter: Parse the selected source delimiter with quote handling, then serialize with the destination delimiter and spreadsheet formula escaping.

Physics & engineering

Two-solution concentration blend

Two-solution concentration blend: Solve low-volume + high-volume = final volume and low-concentration × low-volume + high-concentration × high-volume = target-concentration × final volume.

Text & writing

Unicode text normalization

Unicode text normalization locally in your browser, with clear input requirements, a worked example and an explanation of the result.

Developer & data

Unpivot wide CSV columns

Unpivot wide CSV columns: Keep the selected identifier; turn every other cell into a separate row with the source column name and cell value.

Developer & data

URL query builder and parser

Build, append or inspect a URL query string with browser-standard encoding, duplicate parameter support and no network request.

Developer & data

UTF-8 text and hexadecimal bytes

UTF-8 text and hexadecimal bytes: Encode text with UTF-8 and format each byte as two hexadecimal digits; decode pairs of hex digits using a fatal UTF-8 decoder.

Developer & data

UUID format and version checker

UUID format and version checker locally in your browser, with clear input requirements, a worked example and an explanation of the result.

Developer & data

vCard 3.0 contact file generator

vCard 3.0 contact file generator: Escape text backslashes, commas, semicolons and line breaks; emit a UTF-8 vCard 3.0 with FN, EMAIL, TEL and ORG fields.

Home & construction

Wallpaper roll quantity

Estimate whole wallpaper rolls from strip height, roll dimensions, trimming and an optional straight-match pattern repeat.

Math & statistics

Weighted median

Weighted median with an explained formula, a worked example and checks for invalid or unsupported inputs.

Business & selling

Weighted supplier scorecard

Weighted supplier scorecard: Require a weight for every score column and a total weight of 100%.

Text & writing

Word frequency counter

Word frequency counter locally in your browser, with clear input requirements, a worked example and an explanation of the result.

Business & selling

Working capital and current ratio

Working capital and current ratio: enter your own figures, see the result and calculation method, and check the model’s assumptions.

Money & borrowing

Year-by-year variable-return drawdown

Year-by-year variable-return drawdown: For each entered year apply its return to the current balance, then take the entered year-end withdrawal.

Math & statistics

Z-score standardization

Express an observation as the number of population standard deviations above or below the mean.

These tools answer common practical questions; this list is not a measured Google popularity ranking. Inputs and file generation stay in your browser.

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