Time Calculator
Add or subtract durations from a time, find the gap between two times, and sum several durations — with midnight crossings shown clearly.
17:30, 5:30 PM or 1730.
2:45, 2h 30m, 90m, or a bare number meaning minutes.
100:00 means one hundred hours; a time of day is not, so 25:00 is refused as a typo rather than silently wrapped to 01:00.How it works
- Choose what you want to calculate.
- Enter times as 17:30, 5:30 PM or 1730; durations as 2:45, 2h 30m or 90m.
- Everything is calculated in whole seconds in your browser, so the totals are exact.
Frequently Asked Questions
What can it calculate?
Adding a duration to a time (08:30 + 02:45 = 11:15), subtracting one (17:30 − 09:45 = 07:45), the difference between two times, the total of several durations, and conversions between hours, minutes and seconds.
What happens when the result crosses midnight?
It is reported. 23:30 + 02:00 gives 01:30 and states that it is the NEXT day — producing "01:30" with no further comment is how a shift or a deadline gets missed. Multiple-day rollovers are counted too.
Why is the arithmetic done in seconds?
Because fractional hours cannot be represented exactly in binary floating point. Working in whole seconds and converting once at the end means a 40-hour total reports exactly 40.00 rather than 39.99999999999999.
What input formats work?
Times as 17:30, 17:30:45, 5:30 PM or 1730. Durations as 2:45, 2h 30m, 90m, or a bare number meaning minutes. A duration’s hours are unbounded, so 100:00 means one hundred hours — unlike a time of day, where 25:00 is a typo and is refused rather than silently wrapped.