Reference formulas and worked examples below keep their stated units. Monetary examples use USD; dimensional examples use US customary units unless labeled otherwise. Metric calculator inputs are converted to these reference units before calculation. Choosing another currency does not convert example amounts or exchange money.
How to use this hours calculator
Enter clock times and the number of calendar days between them. For an overnight shift, set Days after start to 1.
How the calculation works
Convert each clock time to minutes since midnight. Elapsed minutes = end minutes − start minutes + days after start × 1,440.
Net minutes = elapsed minutes − break minutes. Divide by 60 for decimal hours.
Hours and minutes split the net duration into whole hours plus the remaining minutes. Decimal hours are displayed to four decimal places.
Worked example
09:00 to 17:30 on the same day is 8 hours 30 minutes. Subtract a 30-minute break for 8 hours, or 8.0000 decimal hours. From 22:00 to 06:00 with one day after start is also 8 hours before breaks.
Limits and assumptions
Calculates clock-time arithmetic with 24-hour days. It does not adjust for daylight saving changes or different time zones, and does not determine payroll or overtime rules.
Frequently asked questions
How do I calculate overnight hours?
Set Days after start to 1. For 10 PM to 6 AM, enter 22:00 and 06:00.
Is 7 hours 30 minutes the same as 7.30 decimal hours?
No. Thirty minutes is half an hour, so the decimal value is 7.5.
What if the start and end times match?
With zero days after start, the duration is zero. With one day after start, it is 24 hours.