Time Duration Calculator
Free time duration calculator: enter a start and end time to get the exact hours and minutes between them - perfect for shifts, billing and time tracking.
About this tool
How long was that shift, really? From 9:00 to 17:30 is not 'about eight hours' - it is exactly 8 hours 30 minutes, and that half hour is money if you bill by the hour. A time duration calculator turns two clock times into a precise duration.
Freelancers, shift workers, and anyone logging hours live by this math. Rounding 'about 8 hours' on every timesheet quietly donates real earnings; exact durations keep billing honest and payroll disputes rare.
How to use
Pick the start time and end time using the time pickers, then press Calculate Duration.
You get the duration as hours and minutes, the total in minutes, and the decimal hours (8.50) that timesheets and invoices expect. Overnight spans are handled automatically - 22:00 to 06:00 correctly reads as 8 hours, not negative 16.
The math behind it
Duration = end time - start time, in minutes; if the result is negative, add 1,440 minutes (24 hours) to wrap past midnight. Hours = floor(minutes / 60); remaining minutes = minutes mod 60.
Decimal hours (minutes / 60) are the lingua franca of payroll: 8 hours 30 minutes becomes 8.50, which multiplies cleanly against an hourly rate.
Frequently asked questions
How do I calculate hours worked overnight?
What are decimal hours and why do timesheets use them?
Should I subtract my lunch break?
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