Time Duration Calculator
Enter a start and end date and time. If the dates match, you get a same-day duration; set different dates and it counts the full days in between plus the leftover time.
Time duration calculator
End is before start — check the dates, or swap them if that was the intent.
Duration
8 hr 30 min
How to calculate time duration manually
Same day: subtract the start time from the end time. 9:15 AM to 5:45 PM is 8 hours 30 minutes.
Spanning days: count the full 24-hour days between the two dates first, then handle the partial day at each end separately. March 8, 11:00 PM to March 12, 8:15 AM is 3 full days (the 9th, 10th, 11th) plus 1 hour from 11 PM to midnight, plus 8 hours 15 minutes from midnight to 8:15 AM — 3 days 9 hours 15 minutes total.
Examples
| Start | End | Duration |
|---|---|---|
| Mar 8, 9:15 AM | Mar 8, 5:45 PM | 8 hr 30 min |
| Mar 8, 10:30 PM | Mar 9, 6:00 AM | 7 hr 30 min |
| Mar 8, 9:00 AM | Mar 10, 9:00 AM | 2 days |
| Mar 8, 11:00 PM | Mar 12, 8:15 AM | 3 days 9 hr 15 min |
One time zone at a time
This calculator assumes both times belong to the same time zone — your device's local clock. It correctly reflects a daylight-saving transition that falls inside the span, because that's still one continuous local clock. What it doesn't do is convert a start time in one zone to an end time in another; if a flight departs 2:00 PM Eastern and lands 4:30 PM Pacific, the actual elapsed time isn't what a naive subtraction of those two clock faces would suggest, because the zones themselves differ by 3 hours.
Duration vs. a calendar difference
This tool measures elapsed clock time — hours and minutes, with full days counted where the span crosses midnight. It isn't calculating a calendar difference in months or years (the way an age or anniversary calculator would), because "months" don't have a fixed number of hours. For a span longer than a few days, expect the answer expressed as total days plus a leftover, not as months and days.
Duration in decimal hours
The result includes decimal hours automatically, which is useful for billing or payroll math — 8 hours 30 minutes converts to 8 + 30/60 = 8.5. For a duration you already have written out as hours and minutes, or need to convert the other direction, see the decimal hours calculator.
When to use a different tool
Tracking an actual work shift with a lunch break or other excluded time? Usecalculate hours worked — it subtracts breaks directly instead of requiring you to compute the gap yourself. Need to calculate pay from a known number of overtime hours? Use the overtime calculator. Adding a duration to a start time instead of finding the gap between two times? Use the add time calculator. Working from 24-hour times and want them in standard AM/PM form first? Use themilitary time converter.
Common mistakes
- Forgetting to change the end date for an overnight or multi-day span — leaving both dates the same produces a negative duration.
- Mixing time zones without adjusting for the offset between them.
- Rounding minutes into an approximate decimal instead of using the exact minutes-to-decimal conversion.
Frequently asked questions
How do I calculate the duration between two times?
Subtract the start from the end. If both fall on the same day, subtract the clock times directly. If the end is on a later date, count the full days in between first, then add the leftover hours and minutes.
Does this handle a span across multiple days?
Yes. Set different start and end dates and the result includes full days, plus the leftover hours and minutes — for example, 3 days 9 hours 15 minutes.
Does this account for daylight saving time?
It uses your device's local clock for both times, so a span crossing a daylight-saving change reflects the actual 1-hour shift your device applies — a 2 AM–4 AM span on a spring-forward night is really 1 hour of elapsed clock time, not 2. What it can't do is convert between two different time zones; enter both times as your local time, or the result will be wrong if start and end are meant to be in different zones.
What's the difference between this and the hours-worked calculator?
This tool finds raw elapsed time between any two moments, with no assumptions about breaks. The calculate hours worked tool is built specifically for a work shift, with break minutes subtracted from the total.
Can I get the answer in decimal hours?
Yes — the result includes the decimal-hours equivalent alongside the days/hours/minutes breakdown.
Does it calculate down to the second?
No, the inputs are to the minute. For second-level precision you would need a stopwatch or a tool built for that granularity.