Time Calculator: Duration, Add & Subtract
Find the time between two clock times, add or subtract hours and minutes from a time, or add up a list of durations. Overnight spans, unpaid breaks and decimal hours for payroll are handled.
Written by Suhaib Hassan. Figures are estimates you can edit. Our methodology.
It converts clock times to minutes since midnight, does the arithmetic on whole minutes, and turns the answer back into hours, minutes and decimal hours.
Clock arithmetic goes wrong around midnight and with breaks. This handles both and gives the decimal hours a timesheet needs.
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Minutes to decimal hours
Payroll usually needs time as hours in decimals. Divide the minutes by 60.
| Minutes | Decimal | Minutes | Decimal |
|---|---|---|---|
| 5 min | 0.08 h | 35 min | 0.58 h |
| 10 min | 0.17 h | 40 min | 0.67 h |
| 15 min | 0.25 h | 45 min | 0.75 h |
| 20 min | 0.33 h | 50 min | 0.83 h |
| 25 min | 0.42 h | 55 min | 0.92 h |
The 7-minute rounding rule. Where an employer rounds to the nearest quarter hour, 1 to 7 minutes round down and 8 to 14 minutes round up to the next quarter. So 8 to 22 minutes count as 15 minutes, 23 to 37 as 30, 38 to 52 as 45 and 53 to 60 as a full hour. Rounding must average out so employees are paid for all time worked.
Formulas
How the numbers are worked out.
Time between two clocks
Convert both times to minutes since midnight, add a day offset if the end is on a later day, and subtract.
elapsed = (end + 1440 × days) − start
net = elapsed − breakAdd or subtract time
Add or subtract the span in minutes, then wrap around 24 hours to get the clock time and the day shift.
result = start ± (days × 1440 + hours × 60 + minutes)Decimal hours
Minutes divided by 60. Pay is decimal hours times the hourly rate.
decimal hours = minutes ÷ 60
pay = decimal hours × rateWorked examples
Illustrative figures, each checked by hand. The first is the default setup.
Shift with a break
8:45 AM to 5:15 PM, 45 minute unpaid break, $30 an hour (the default).
net = 8 h 30 m − 45 m = 7 h 45 m = 7.75 h
pay = 7.75 × $30 = $232.50
Night shift
10:00 PM to 6:30 AM the next day, 30 minute break.
net = 8 h 00 m = 8.00 h
Add time
9:00 AM plus 2 hours 45 minutes.
How to calculate time
- Choose whether to find the time between clocks, add or subtract, or add up durations.
- Enter the times. For a shift that ends after midnight, set the end to the next day.
- Add the unpaid break and an hourly rate if you want pay.
- Read the duration in hours and minutes, decimal hours and total minutes.
For a full weekly timecard with overtime, use the Hours Calculator. Check local rules on rounding and breaks before relying on the payroll figures.
By Suhaib Hassan · Reviewed 29 September 2026 · How CalculatePilot verifies formulas →
Sources
- U.S. Department of Labor, 29 CFR 785.48(b), rounding of working time.
- NIST, Time and Frequency Division, definition of the second and the day.
- ISO 8601, Date and time format.
Frequently asked questions
How do I calculate time between two times?
Convert each to minutes since midnight and subtract. If the end is earlier than the start the span crosses midnight, so add 24 hours to the end.
How do I convert minutes to decimal hours?
Divide the minutes by 60. 45 minutes is 0.75 hours, and 7 hours 45 minutes is 7.75 hours.
What is the 7-minute rule?
A payroll method that rounds working time to the nearest quarter hour. Up to 7 minutes rounds down, 8 minutes or more rounds up.
How do I subtract time?
Choose Subtract, enter the hours and minutes to take away, and the result shows the earlier clock time and how many days back it falls.
Does it handle daylight saving?
No. It does clock arithmetic on a 24-hour day, so a shift across a daylight saving change will be an hour out.
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