An hours calculator finds the hours and minutes between a start time and an end time, including shifts that run past midnight. Formula: minutes = end − start (+24 h if end < start) − break; hours = minutes ÷ 60. 9:00 to 17:30 is 8.5 hours.
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How to use the hours calculator
- Enter the start hour and minute on a 24-hour clock.
- Enter the end hour and minute.
- Read the elapsed time in decimal hours and minutes.
How the hours calculator works
The hours calculator finds the time between a start time and an end time. It converts both times to minutes after midnight, subtracts, and adds 24 hours if the end time is earlier than the start, which handles overnight shifts:
- Minutes = (end hour × 60 + end minutes) − (start hour × 60 + start minutes)
- If negative, add 1,440 minutes (24 hours)
- Decimal hours = minutes ÷ 60
Enter times on a 24-hour clock, so 5:30 PM is 17:30.
Hours calculator worked example
A shift from 9:00 to 17:30 is 1,050 − 540 = 510 minutes, or 8.5 hours. An overnight shift from 22:00 to 6:00 gives 360 − 1,320 = −960 minutes; adding 1,440 gives 480 minutes, or 8 hours.
| Start | End | Hours | Minutes |
|---|---|---|---|
| 9:00 | 17:00 | 8.00 | 480 |
| 9:00 | 17:30 | 8.50 | 510 |
| 8:15 | 16:45 | 8.50 | 510 |
| 7:00 | 15:30 | 8.50 | 510 |
| 6:00 | 14:20 | 8.33 | 500 |
| 12:00 | 20:45 | 8.75 | 525 |
| 22:00 | 6:00 | 8.00 | 480 |
| 23:30 | 7:15 | 7.75 | 465 |
Breaks and lunch
Enter unpaid break minutes and the hours calculator subtracts them, showing worked time in decimal hours and in hours and minutes. Under the Fair Labor Standards Act, the Department of Labor explains that short rest breaks of about 5 to 20 minutes count as hours worked, while bona fide meal periods, usually 30 minutes or more when you are fully relieved of duty, do not. A 9:00 to 17:30 day with a 30-minute unpaid lunch is 8 paid hours.
Adding up a week
Run the hours calculator for each day and add the decimal results. Five days of 8.5 hours is 42.5 hours. Under federal law, covered nonexempt employees earn overtime of at least 1.5 times their regular rate for hours over 40 in a workweek, so 2.5 of those hours would be overtime. Some states also have daily overtime rules.
Tips
- Shifts of 24 hours or longer need to be split, because the tool assumes the end is within a day of the start.
- Enter hours from 0 to 23 and minutes from 0 to 59.
- Keep your own time records; the DOL recommends workers track their hours.
Rounding time and payroll
Many employers record time in tenths or quarters of an hour. The Department of Labor allows rounding to the nearest 5 minutes, tenth or quarter hour, as long as it averages out so employees are paid for all the time they actually work over time. To turn minutes into decimal hours, divide by 60: 15 minutes is 0.25 hours, 20 minutes is 0.33 hours and 45 minutes is 0.75 hours. Multiply decimal hours by the hourly rate to estimate pay; 8.5 hours at $20 an hour is $170 before taxes.
Common uses of the hours calculator
People use the hours calculator to check timesheets, log volunteer or study time, plan babysitting or tutoring sessions and work out how long a trip or event lasted. Freelancers often bill in decimal hours, so the decimal result can go straight onto an invoice: 2 hours 40 minutes is 2.67 hours. If you work several separate blocks in a day, run each block and add the results, then subtract unpaid breaks (or enter them in the break field) to get your paid time.
Converting AM and PM times
To use 24-hour time, keep morning hours as they are and add 12 to afternoon and evening hours from 1 PM onward, so 1:15 PM becomes 13:15 and 11:45 PM becomes 23:45. Midnight is 0:00 and noon is 12:00. Mixing up AM and PM is the most common reason for a result that is 12 hours off.
Related converters and calculators
Related calculators:
- Time card calculator: time cards
- Time duration calculator: durations
- Time calculator: adding time
- Overtime tax calculator: overtime
Sources
DOL Fact Sheet #22: Hours worked under the FLSA; U.S. Department of Labor: Overtime pay.
Time difference between two times
Enter a start time and end time to get hours and minutes elapsed. If the end time is earlier than or equal to the start time, Calcenzo treats the span as crossing midnight (a full 24 hours when the times are equal).
How elapsed time is computed
Convert each clock time to minutes from midnight, subtract, and if needed add 24 hours when the shift crosses midnight. Display hours = floor(total minutes ÷ 60); remaining minutes = total minutes mod 60. This is clock time math, not a timesheet with unpaid breaks unless you subtract breaks yourself.
Formula and method
minutes = end − start (+24 h if end < start) − break; hours = minutes ÷ 60.
Hours 0–23 and minutes 0–59 are validated; the break must be zero or more and no longer than the span. Shows decimal hours and h:min.
Questions about this calculator
How many hours is 9 to 5:30?
8.5 hours.
Does it handle overnight shifts?
Yes, it adds 24 hours when the end is earlier than the start.
Does it subtract lunch?
Yes, enter your unpaid break in minutes.
How do I convert minutes to decimal hours?
Divide by 60.
Are short breaks paid?
Under the FLSA, breaks of about 5 to 20 minutes count as work time.
Check the assumptions and units before relying on a result. Financial, tax and health estimates do not replace advice for your individual circumstances.
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