Our Calculator

Time Duration Calculator

Calculate elapsed time between a start and end time, including overnight spans. See hours and minutes, decimal hours and total minutes.

No signup requiredMethod and rounding explainedEditorial standards and sources

Enter start and end times

Choose next day when the ending time is after midnight.

Your result

Elapsed time

Updates automatically as you change the inputs.

Elapsed time
8 hr 30 min
Decimal hours8.5
Total minutes510

How to use the time duration calculator

Enter start and end clock times. Select next day for an overnight interval such as 10:00 PM to 6:00 AM.

Time-duration method

Calculation formulaTime-duration method
Used for the result above
Duration minutes = end minutes after midnight − start minutes after midnight, plus 1,440 minutes when the selected end is on the next day.

Decimal hours divide total minutes by 60. For example, 7 hours 30 minutes equals 7.5 decimal hours.

Example: Lucas measures an overnight interval

Lucas starts at 10:00 PM and finishes at 6:00 AM the next day. Selecting Next day produces 8 hours, equivalent to 480 minutes.

The same clock times on the same day would put the end before the start. This tool compares clock readings and does not adjust for time zones or daylight-saving changes.

Read decimal hours correctly

From 9:00 AM to 5:30 PM is 8 hours 30 minutes, or 8.5 decimal hours. It is not 8.30 decimal hours: 30 minutes is half an hour.

For 10:00 PM to 6:00 AM, select Next day to get 8 hours. To calculate time duration with breaks, use the related Hours Worked Calculator, which subtracts unpaid break minutes.

Time duration with breaks or calendar dates

A start time of 09:15 and an end time of 17:45 gives 8 hours 30 minutes, or 8.5 decimal hours. For 22:00 to 06:00, choose the overnight option to count across midnight.

Use the Hours Worked Calculator to subtract unpaid breaks. A 30-minute unpaid break reduces 8 hours 30 minutes to 8 paid hours. For whole calendar days between dates, use the Date Difference Calculator; this clock-time tool does not model a multi-day date-and-time interval.

Assumptions and limitations

What the estimate assumes

Does not apply time zones, daylight-saving transitions, or dates.

Time Duration Calculator FAQs

How do I calculate an overnight time span?

Select that the end time occurs on the next day.

What are decimal hours?

Total minutes divided by 60. Thirty minutes equals 0.5 hour.

Does this subtract breaks?

Use the Hours Worked Calculator when you want to subtract an unpaid break.

Does daylight saving time affect this?

This is a clock-time calculation without dates or time zones, so DST is not modeled.

Clock-time calculation only. Dates, time zones, and daylight-saving transitions are not included.