How to calculate hours between two times

Updated November 15, 2026 · Worked examples use whole minutes

Write both times on a 24-hour clock and subtract the start from the end. If the end minutes are smaller, borrow one hour as 60 minutes. From 7:40 am to 3:25 pm is 15:25 − 7:40, which becomes 14:85 − 7:40, or 7 hours 45 minutes.

Calculate it step by step

1. Convert both times to a 24-hour clock: add 12 to pm hours from 1 pm onwards.
2. If the end is earlier than the start, add 24 hours to the end.
3. Subtract the minutes. If the end minutes are smaller, borrow 60 minutes from the end hours.
4. Subtract the hours. Divide the leftover minutes by 60 if you need decimal hours.

Worked example

A shift from 6:50 am to 2:35 pm: 14:35 − 6:50 becomes 13:95 − 6:50, which is 7 hours 45 minutes, or 7.75 hours. With a 15-minute unpaid break it is 7 hours 30 minutes, or 7.50 hours.

Check your own shifts in the time card calculator

What if the end time is after midnight?

When the end time is earlier on the clock than the start, the span crosses midnight. Add 24 hours to the end before subtracting. From 11:30 pm to 7:15 am is 31:15 − 23:30, or 7 hours 45 minutes.

A quick check is to count up from the start to the next whole hour, then whole hours, then the leftover minutes. From 7:40 am, 20 minutes reaches 8:00, seven hours reaches 3:00 pm and 25 more minutes reaches 3:25 pm: 7 hours 45 minutes.

Further reading

• NIST frequently asked questions about times of day