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This calculator is designed to help you perform time calculations such as adding and subtracting time and converting time formats.

  1. Enter your time variables by clicking on the calculator buttons on the screen. You can enter a string of digits to represent seconds, or separate digits using the : button to represent days, hours, minutes and seconds (D:H:M:S). For example, enter 500 for 500 seconds, or 1:12:30:50 for 1 day, 12 hours, 30 minutes and 50 seconds.
  2. The + or buttons allow you to add or subract two or more time values.
  3. The calculator works in 24-hour time so AM/PM is not used. For example, to calculate hours worked if you started at 7:30AM and finished at 3:30PM, first convert PM times to 24-hour time by adding 12 hours. Therefore, you would calculate 3:30:00 + 12:00:00 - 7:30:00 resulting in 8 hours. See the notes below if you need more information on how to enter these time values.
  4. If you enter a number of seconds and click the = button or press the Enter key on your keyboard, the calculator will convert those seconds into D:H:M:S time format. For example, enter 86400 to see the result converted to 1 day.
  5. You can mix time formats in your calculations, such as using seconds for one value and D:H:M:S format for another.
  6. As an alternative, you can enter some values with your keyboard. See below for details.
  7. Click the = button to see your result.

You may also like to try these calculators:

Click here to try our other Time/Date Calculators.



Here is a list of some of the keyboard shortcuts that can be used to enter values instead of clicking the buttons on the calculator above.

Keyboard Function
Esc Clear (C) and All Clear (AC)
0 1 2 3 4
5 6 7 8 9
Insert corresponding digit
+ Add
- Subtract
: Time value separator
Backspace Delete last character
Number + Enter Convert seconds into D:H:M:S time format
Enter or Return Calculate result

Please note, some keyboard shortcuts don't work in some browsers.

For reference, an hour has 3,600 seconds, a day has 86,400 seconds, a week has 604,800 seconds and a non-leap year has 31,536,000 seconds.

To calculate 3:30:00 + 12:00:00 - 7:30:00, the calculator button sequence would be:




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