Time Duration Calculator — Free Online Tool
How long did that take? Enter a start and end time — or full dates with times — to get the precise elapsed duration in hours, minutes, and seconds.
What is the Time Duration Calculator?
Time math is annoying because hours and minutes don't work in base 10: 1:45 + 0:30 isn't 1:75, it's 2:15. This calculator handles the carrying for you across any two timestamps, including multi-day spans when you include dates.
Typical uses: billing hours for freelance work, timing workouts or study sessions, calculating shift lengths, measuring travel time, or checking how long an event ran. For shifts crossing midnight, include the date (or set the end date to the next day) so the calculator counts correctly.
How to use this calculator
- Pick the start date and time.
- Pick the end date and time.
- Click Calculate Duration for the full breakdown.
Formula
Frequently asked questions
How do I calculate hours between two times?
Enter both as date-times and subtract — this tool does it, handling the 60-minute carry automatically.
What about overnight shifts?
Include dates: set the end date to the next day. Without dates the tool can't know midnight was crossed.
Can it handle multi-day durations?
Yes — with dates included, any span works, reported in hours/minutes/seconds totals.
Does it account for daylight saving or time zones?
No — it treats both timestamps in your browser's local time. For DST-crossing spans, verify manually.