Time Addition and Subtraction Calculator
Convert durations to seconds, add/subtract, then convert back to hours, minutes and seconds.
Inputs and units
- First duration (HH:MM:SS): Enter your value in the format and unit shown.
- Operation: Choose Add, Subtract.
- Second duration (HH:MM:SS): Enter your value in the format and unit shown.
Calculation method
Convert durations to seconds, add/subtract, then convert back to hours, minutes and seconds.
Worked example
The example values are: First duration (HH:MM:SS) = 2:30:00; Operation = add; Second duration (HH:MM:SS) = 1:45:00
- Duration: 4:15:00
- Decimal hours: 4.25
- Total seconds: 15,300
Assumptions and limitations
Check that the inputs and units describe your situation.
Using your result
Select Calculate after changing inputs. Copy result copies the displayed output; Download result saves a text file. Reset returns the form to its example inputs. Calculations run in your browser.
Time Addition and Subtraction Calculator FAQs
What method does this calculator use?
Convert durations to seconds, add/subtract, then convert back to hours, minutes and seconds.
What should I check before using the result?
Check that the inputs and units describe your situation.