Time Calculator
Add or subtract multiple time durations in hours, minutes and seconds. Get decimal hours, total minutes and total seconds instantly.
Add and subtract time durations
Combine multiple hours, minutes and seconds or type a compact expression.
What this time calculator is for
This calculator adds and subtracts durations: amounts of time such as 2 hours 30 minutes, 45 minutes, or 20 seconds. It is useful when you have several blocks of time and want one total without converting everything to minutes first.
The result is shown in a normalized hours-minutes-seconds format and also as decimal hours, total minutes and total seconds. That makes the same calculation useful for planning, spreadsheets, logs and any system that expects a numeric duration.
If your question starts with two clock times, such as “How long is 8:45 AM to 5:20 PM?”, use the Time Duration Calculator. This page is for adding or subtracting amounts of time, not comparing clock times.
How time addition and subtraction works
DateTimeWise converts each duration to seconds, applies the plus or minus operation, and then converts the total back to a readable duration. The conversion is based on 60 seconds per minute and 60 minutes per hour.
Values do not need to be pre-normalized. For example, you can enter 90 minutes and the result can be displayed as 1 hour 30 minutes. A total can also be longer than 24 hours because a duration is not limited to a single day.
Worked examples
| Calculation | Result | Decimal hours |
|---|---|---|
| 2h 30m + 1h 45m | 4h 15m | 4.25 |
| 8h − 45m | 7h 15m | 7.25 |
| 90m + 30m | 2h | 2.00 |
| 1h 20m + 45s | 1h 20m 45s | about 1.3458 |
Common ways to use the calculator
Add several activities
Enter each duration as a separate row when you want to total study sessions, exercise sessions, project tasks, media runtimes or other blocks of elapsed time.
Subtract breaks or interruptions
Use a minus row or a negative expression when a block of time should be removed from the total. For employee shifts, lunch breaks, overtime and estimated pay, use WorkHoursTool, which is designed specifically for work-hour calculations.
Convert the result for another system
Some systems use decimal hours instead of hours and minutes. A result of 2 hours 45 minutes is 2.75 decimal hours because 45 ÷ 60 = 0.75. If you only need a two-way converter, open the Hours & Minutes Calculator.
Time calculator FAQ
Can I enter more than 60 minutes?
Yes. You can enter values such as 90 minutes or 150 minutes. The result is normalized into hours, minutes and seconds.
Can the result be negative?
Yes. If the durations you subtract are larger than the durations you add, the final total is negative.
What are decimal hours?
Decimal hours express minutes as a fraction of an hour. For example, 30 minutes is 0.5 hour and 45 minutes is 0.75 hour.
Can the result be longer than 24 hours?
Yes. This calculator works with durations, so totals can span multiple days. The normalized result includes a day component when needed.
Does this calculate the time between two clock times?
No. For a start time and end time, including overnight spans, use the Time Duration Calculator.
For more detail about the calculation rules used across the site, see How DateTimeWise Calculations Work.