Free Hours Calculator
Find the hours between two times, including overnight and breaks, add or subtract durations in h:mm, and convert to decimal hours.
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How to calculate hours between two times
Find the hours between two clock times minus breaks, add or subtract durations, and convert to decimal hours.
- Enter a start time and end time, such as 8:45 AM and 5:15 PM or 08:45 and 17:15.
- Add a break in minutes if you want it taken off.
- Read the total in h:mm, decimal hours and minutes; overnight spans are handled automatically.
- In Add or subtract time, enter durations like 1:30, 1h 30m or 1.5 and choose plus or minus for each line.
- Use the converter to switch between decimal hours and h:mm.
When to use an hours calculator
Adding up time is surprisingly awkward because hours have 60 minutes, not 100. An hours calculator handles everyday questions like how long a shift lasted, how many hours a trip took, how much time a project has used, or how long it was between two events on a clock.
This tool has three parts. The first finds the time between two clock times, including spans that cross midnight, and can subtract a break. The second adds and subtracts a list of durations, which is handy for totaling a week of study sessions or billable tasks. The third converts between decimal hours and hours and minutes.
Freelancers and contractors often need decimal hours for invoices, while people reading a clock think in hours and minutes. Switching between the two by hand invites small errors that add up over a month, so having both formats side by side saves time and avoids billing mistakes.
Worked example: a day shift, a night shift and a weekly total
Enter 8:45 AM to 5:15 PM with a 30 minute break. The span is 8 hours 30 minutes before the break, so the result is 8:00, or 8 decimal hours and 480 minutes. For a night shift, enter 10:00 PM to 6:30 AM with a 45 minute break. Because the end is earlier than the start, the calculator treats it as the next morning: 8 hours 30 minutes in total, 7:45 after the break, which is 7.75 decimal hours.
In the add or subtract section, enter Monday 7:30, Tuesday 8:15 and Wednesday 6:45, then subtract 0:30 for a long lunch. The total is 22:00, which is 22 decimal hours or 1,320 minutes. In the converter, 7.75 decimal hours equals 7:45, and 7:45 equals 7.75 hours.
How the times are calculated
Each clock time is turned into minutes after midnight. 12:00 AM is 0 minutes, 12:00 PM is 720 minutes, and a time without AM or PM is read on the 24-hour clock. The span is the end minus the start. If that is negative, or if you tick the next day option, 1,440 minutes, one full day, are added. The break is then subtracted.
Durations are also stored as minutes, so they add and subtract exactly. Results are shown as h:mm, as decimal hours, which is minutes divided by 60, and as total minutes. The 12-hour and 24-hour buttons change how parsed times are displayed back to you.
Common mistakes to avoid
The classic mistake is treating minutes as decimals. Seven hours and 45 minutes is 7.75 hours, not 7.45, and multiplying 7.45 by an hourly rate underpays you. Always convert to decimal hours before doing pay math.
Another mistake is leaving off AM or PM. Typing 5:15 means 5:15 in the morning on the 24-hour clock, so an 8:45 start would look like a night shift. Finally, this tool does not adjust for daylight saving time changes, so a span that crosses a clock change can be an hour off. For weekly overtime and pay, use the time card calculator.
Useful tips and limitations
- Write times with AM or PM to avoid mix-ups; a time without them is read as 24-hour.
- Use decimal hours when multiplying by an hourly rate; 7:45 is 7.75 hours, not 7.45.
- Use the minus option in the duration list to take off unpaid time or time already billed.
- Copy the results to paste a clear summary into a timesheet note or invoice.
Common questions
How does the hours calculator handle overnight times?
If the end time is earlier than the start time, it is treated as the next day. For example, 10:00 PM to 6:30 AM is 8 hours 30 minutes. Tick End is on the next day for a span of 24 hours or more.
What duration formats does the hours calculator accept?
You can type h:mm such as 2:45, hours and minutes such as 2h 45m or 45m, or decimal hours such as 2.75. Put a minus sign in front or choose minus to subtract.
How is the hours calculator different from the time card calculator?
The hours calculator is a general tool for time between two clock times and adding durations. The time card calculator totals a week of shifts with overtime and estimated pay.
Does the hours calculator account for daylight saving time?
No. It works with clock times on a plain 24-hour day, so a span across a daylight saving change may be off by one hour.
How do I enter midnight and noon in the hours calculator?
Type 12:00 AM or 00:00 for midnight and 12:00 PM or 12:00 for noon. 24:00 is also accepted as midnight.
Can the hours calculator show a negative total?
Yes. If the durations you subtract are larger than the ones you add, the total is shown with a minus sign.
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