Time calculator: add or subtract hours, minutes and days

Time calculator

Add or subtract days, hours, minutes and seconds to a time or a date, or add up a list of durations. Results appear as you type.

Start date (optional)Start timeOperation

DaysHoursMinutesSeconds

This is clock arithmetic: no time zone, so no daylight-saving change is applied. To count real elapsed time between two places use the flight arrival calculator or the converter.

Result

11:30:00

Same day

09:00:00 + 2 h 30 min: that is 2.50 hours, or 9,000 seconds.

How it works

How the time calculator works

Pick a start time, choose add or subtract, and enter the days, hours, minutes and seconds. The calculator turns everything into seconds, adds or subtracts, and writes the result back as a clock time. If you also give a start date, the result is a full date and weekday, and it knows how many days each month has and which years are leap years.

The second mode adds up a list of durations, such as the shifts of a week or the lengths of the tracks on an album. Each line may be written as hours and minutes (1:30), with units (2h 15m) or as decimal hours (1.5h). The total is shown as hours, minutes and seconds, and as decimal hours for timesheets.

Clock time, not elapsed time in a place

Adding 6 hours to 22:00 gives 04:00 the next day on the clock. If the clocks of a place change in between, the real time elapsed is different: in the United States the night clocks go forward is one hour shorter. This calculator deliberately ignores such changes, because it has no place to apply them to; use the flight arrival calculator when the time zones matter.

Everything is calculated in your browser; nothing you type is sent or stored. The address of this page changes as you type so that you can copy it and share the same result.

Worked examples

22:30 + 3 h 45 min = 02:15 (1 day later)
08:00 − 1 h 15 min = 06:45
28 February 2027 18:00 + 1 d 6 h = 2 March 2027 00:00
1:45 + 2:30 + 0:50 = 5:05

Questions

Good to know

How do I add hours and minutes to a time?

Enter the start time, leave the operation on add, and type the hours and minutes. For example 09:15 plus 2 hours 45 minutes is 12:00. If the total passes midnight the result shows how many days later it falls.

How do I add up several durations, such as a week of hours?

Open “Add up durations” and put one duration on each line, for example 7:30, 8h and 6h 45m. The total appears as hours, minutes and seconds, and as decimal hours (for payroll, 7 h 30 min is 7.5). For shifts with start and end times use the hours calculator.

Does the time calculator handle daylight saving time?

No. It adds on the clock, as if every day had 24 hours. On the night clocks change, the real time elapsed is one hour more or less. The flight arrival calculator uses the time-zone database and counts such changes correctly.

Can I subtract a time from a time?

To find how long it is from one time to another, use the hours calculator: it also handles shifts that pass midnight and takes breaks off. To subtract a duration from a time, use the subtract operation here.

Time calculator

How the time calculator works

Clock time, not elapsed time in a place

Good to know

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