Add, subtract, multiply, or divide time in hours, minutes, seconds, and milliseconds. Free time calculator for work hours, race splits, and durations.
This time calculator adds, subtracts, multiplies, or divides durations in hours, minutes, seconds, and milliseconds — instantly, without leaving the page.
How to calculate time in 3 steps:
- Choose a mode: Add, Subtract, Multiply, or Divide.
- Enter each duration in hours, minutes, seconds, and optional milliseconds.
- Read the total instantly, including decimal hours.
It works well for work shifts, media runtimes, race splits, project timing, and any other duration math that needs hours, minutes, seconds, and milliseconds.
Common tasks include adding hours and minutes, subtracting one duration from another, converting a result to decimal hours, and scaling a time value for repeated laps, shifts, clips, or tasks.
Examples
Add 1 h 45 m and 2 h 30 m to get 4 h 15 m.
Subtract 3 h 20 m minus 1 h 50 m to get 1 h 30 m.
Multiply 02:30:00 by 1.5 to get 03:45:00.
How to add time
Use Add mode for simple duration sums. Enter each time on its own row, then let the calculator carry minutes, seconds, and milliseconds automatically. You can keep precision high with milliseconds on, or hide that field when you only need hours, minutes, and seconds.
For a workday, you might add a shift, a break, and overtime on separate rows. The result updates live as you edit.
How to multiply time
Use Multiply mode when you need to scale a duration by a factor, such as converting one race split into multiple laps or extending media runtime. Use Divide mode to split a total duration evenly across people, tasks, or sessions.
The time input stays compact as HH:MM:SS.MS, so the calculator behaves like a spreadsheet without forcing a wide desktop layout on mobile.
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Time Calculator FAQ
Add mode sums each row as a separate duration. Enter hours, minutes, seconds, and optional milliseconds on each line, then the calculator carries overflow automatically, so 90 minutes becomes 1 h 30 m internally.
Switch to Multiply or Divide, enter one compact time value in HH:MM:SS.MS format, and provide a single number. For example, 02:30:00 × 1.5 gives 03:45:00.
Switch to Subtract mode, enter the starting duration on the first row and the duration to remove on the second. The calculator carries borrowing automatically, so subtracting 1 h 50 m from 3 h 20 m gives 1 h 30 m.
Yes. Leave the hours field at 0 or hide it if you do not need it, and enter only minutes and seconds. The calculator still carries overflow correctly, so 90 seconds becomes 1 minute 30 seconds.
Yes. Turn on the milliseconds field for high-precision timing, such as race splits or lap times, alongside hours, minutes, and seconds.
Yes. Use Add mode to sum a shift, a break, and any overtime on separate rows, then read the total in decimal hours for payroll or timesheet entry.
Decimal hours express minutes as a fraction of an hour, such as 1 h 30 m = 1.5 decimal hours. The calculator shows this automatically next to the total, which is useful for payroll and billing.
Yes. The multiplier or divisor can be a decimal, such as 1.5 or 0.75, not just a whole number.
