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Time Duration Calculator
This time duration calculator finds how much time passes between a start time and an end time, in hours, minutes, and seconds, and in decimal hours for timesheets and billing. Add an optional break to deduct unpaid time, and use the add-and-subtract mode to combine two durations — for example, adding two work sessions together or subtracting a lunch break from a shift. Enter a date with each time when a period crosses midnight.
If the end time is earlier than the start time on the same date, the calculator assumes the period runs overnight to the next day.
How it works
The duration between two times is simply the end minus the start, but the details are what trip people up: a shift that crosses midnight, a 30-minute lunch that should not count as work, and a total that payroll wants in decimal hours rather than hours and minutes. This calculator handles all three. Give it a start and an end, each with a date and a time, and it returns the gap in hours, minutes, and seconds, plus the decimal-hours figure — so 8 hours 30 minutes also shows as 8.50 hours.
When the end time is earlier than the start time on the same date, the calculator assumes the period runs overnight and adds a day to the end — a shift from 10:15 PM to 2:45 AM is 4 hours 30 minutes, not a negative number. If you would rather forbid that, choose Same day only and it will flag the input instead. The break field deducts unpaid time from the total: a 9:00 AM to 5:30 PM shift is 8 hours 30 minutes on the clock, and with a 30-minute lunch deducted it is 8 hours of work.
The add-and-subtract mode works with durations rather than clock times. Enter two durations in hours, minutes, and seconds and choose Add or Subtract: 2 hours 30 minutes plus 1 hour 45 minutes is 4 hours 15 minutes, and 5 hours minus 45 minutes is 4 hours 15 minutes. It carries minutes into hours automatically, so you never have to work out 75 minutes by hand. Use it to total a week's sessions, add a workout to a warm-up, or subtract a break from a recording session. Note the boundary of this tool: it measures the time between two clock times, not the number of calendar days between two dates — for day counts, use a date-difference tool instead.
Worked example
You work a shift from 9:00 AM to 5:30 PM on January 15, 2026, with a 30-minute lunch break. How many hours did you work?
Step 1: Enter the start as January 15, 2026 at 9:00 AM and the end as January 15, 2026 at 5:30 PM.
Step 2: Subtract the start from the end: 5:30 PM minus 9:00 AM is 8 hours 30 minutes.
Step 3: Deduct the 30-minute break: 8 hours 30 minutes minus 30 minutes is 8 hours 0 minutes.
Step 4: Convert to decimal hours for a timesheet: 8 hours is 8.00 hours.
The tool gives exactly this result: 8 hours 0 minutes (8.00 decimal hours, 480 minutes). An overnight check works too: 10:15 PM to 2:45 AM the next day gives 4 hours 30 minutes.
FAQ
How do I calculate the duration between two times?
Subtract the start time from the end time. For example, 9:00 AM to 5:30 PM is 8 hours 30 minutes. If the end time is earlier than the start time, add 12 or 24 hours depending on whether the period crosses noon or midnight — this calculator does that automatically when the end falls on the next day. Enter both times above and it shows the answer in hours, minutes, seconds, and decimal hours.
How do I calculate work hours with a lunch break?
Find the total time from clock-in to clock-out, then subtract the break. A 9:00 AM to 5:30 PM shift is 8 hours 30 minutes, minus a 30-minute lunch is 8 hours of work. Put the break in minutes in the break field on this page and it is deducted for you. Paid breaks should not be deducted — only time you were actually off the clock.
What are decimal hours and why do timesheets use them?
Decimal hours write time as a single number with a decimal point instead of hours and minutes: 8 hours 30 minutes is 8.50 hours, because 30 minutes is half an hour. Payroll systems use them because multiplying hours by an hourly rate is simple arithmetic with decimals. To convert, divide the minutes by 60 and add the hours: 45 minutes is 0.75 hours.
How do I add two durations together?
Add the seconds, then the minutes, then the hours, carrying over every 60. For example, 2 hours 30 minutes plus 1 hour 45 minutes is 4 hours 15 minutes, because 30 + 45 is 75 minutes, which is 1 hour 15 minutes. Switch this calculator to Add / subtract durations mode and it does the carrying for you.
What if my shift crosses midnight?
Enter the end date as the next day, or leave both dates the same and let the calculator assume the period runs overnight — a 10:15 PM start and a 2:45 AM end is 4 hours 30 minutes. This tool measures the time between two clock times; if you need the number of calendar days between two dates instead, use a date-difference calculator.