Advanced date and time calculationsElapsed time with zones, clock differences, averages, sorting and interval splitting.
Details of the first result
Dates & time
How it works
A duration describes how much time passes, not a calendar date. Fixed units have exact relationships: one minute is 60 seconds, one fixed day is 24 hours. Calendar months have variable lengths.
What you can do
Convert, sum or subtract fixed durations, including decimal units, ISO 8601 and HH:MM:SS.
How to use it
- Choose convert each, sum, or first minus second. Choose an input unit or HH:MM:SS / ISO duration, then paste one value per line. Choose an output unit or format and calculate. Subtraction needs exactly two lines.
- Check the result and its notes. Copy or download only after calculating; any edit clears the old result.
Errors and limits
Nanoseconds stay exact. Decimal output that repeats is truncated after 18 places and labelled. HH:MM:SS hours may exceed 23. P1M and P1Y are rejected; use the Date Calculator for calendar months and years.
All input stays in this tab. TXT files must be UTF-8; bulk input is limited to 200,000 characters and 10,000 lines.
Frequently asked questions
Is 1.5 hours the same as 1 hour 50 minutes?
No. Half an hour is 30 minutes, so 1.5 hours is 90 minutes or 01:30:00. For 1 hour 50 minutes, enter 01:50:00 in HH:MM:SS mode or PT1H50M in ISO mode.
Are my dates uploaded or saved?
No. These calculations run in your browser. Inputs are not added to the address, stored between visits or sent to a server. Copy and download save only when you ask.