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.
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Dates & time
Choose a tool. The method, example and assumptions are included.
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.
Dates & time
Add or subtract days
Add or subtract days: Add an integer number of UTC calendar days
Dates & time
Age on a date
Calculate age in years, months and days, with total elapsed days. The as-of date starts at today in your local time zone.
Dates & time
Business days with an entered holiday list
Business days with an entered holiday list: Count Monday–Friday in [start,end), excluding unique dates from the entered holiday set.
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.
Dates & time
Date difference
Date difference: Signed calendar days = (UTC end − UTC start)/86,400,000; optional inclusive end
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.
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.
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.
Dates & time
ISO week number
ISO week number: ISO 8601: Monday starts the week; week 1 contains January 4
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.
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.
Dates & time
Monthly recurring date schedule
Monthly recurring date schedule with editable inputs, an explained method, a worked example and clearly stated output limits.
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.
Dates & time
Unix timestamp converter
Unix timestamp converter: Unix seconds count elapsed time since 1970-01-01T00:00:00Z; offset required for ISO input
Dates & time
Weekday count
Weekday count: Count Monday–Friday in [start,end); no holiday exclusions
Dates & time
Work shift hours and unpaid breaks
Calculate paid shift hours and minutes from start/end times, unpaid breaks and an explicit overnight option.