Method guide
How to Calculate Hours Between Two Times
Convert both clock times to minutes after midnight, subtract Start from End, add 1,440 minutes when the interval crosses midnight, subtract any break, then convert the remaining minutes back to hours and minutes.
Quick answer
For a same-day span, use End minutes − Start minutes. For an overnight span where End is earlier, use End minutes + 1,440 − Start minutes. Then subtract the break.
1. Convert each time to minutes after midnight
Multiply the hour by 60 and add the minute. For 08:30: 8 × 60 + 30 = 510. For 17:15: 17 × 60 + 15 = 1,035.
2. Subtract same-day times
1,035 − 510 = 525 minutes, which is 8h 45m gross.
3. Handle an overnight interval
For 22:00 to 06:00, End is earlier than Start. Add one 24-hour clock cycle: 360 + 1,440 − 1,320 = 480 minutes, or 8 hours.
4. Subtract a break
If the gross span is 525 minutes and the break is 30 minutes, net time is 525 − 30 = 495 minutes.
5. Convert minutes back to hours and minutes
Divide by 60. For 495 minutes, the whole-hour quotient is 8 and the remainder is 15, so the result is 8h 15m.
6. Convert to decimal hours
Divide total minutes by 60. 495 ÷ 60 = 8.25. A result such as 7h 50m becomes about 7.8333 decimal hours; 50 clock minutes is not “.50 hours.”
Standard worked example
08:30 to 17:15 with a 30-minute break: gross 525 minutes, net 495 minutes, result 8h 15m / 8.25 hours.
Overnight worked example
22:00 to 06:00 with a 30-minute break: gross 480 minutes, net 450 minutes, result 7h 30m / 7.5 hours.
Why identical clock times are ambiguous
09:00 to 09:00 could mean no elapsed time or a full day. A calculator with no date/day-offset input cannot distinguish those cases safely.
Limits of this method
This is fixed clock arithmetic for one span under 24 hours. It does not model dates, time zones, daylight-saving changes, leap seconds, payroll rounding, or labor rules.