How to use the duration calculator
- Choose add, subtract, or multiply.
- Enter normalized duration parts and, when multiplying, a multiplier.
- Select Calculate. Edit any input to clear the previous result.
How the calculation works
Each duration is converted to seconds. The selected operation is applied, then the total is normalized back to hours, minutes, and seconds.
Examples
1:45:30 + 0:30:45 = 2:16:15.
0:30:00 − 1:00:00 = −0:30:00. Negative results keep one leading minus sign.
Limits
- This tool calculates lengths of time, not times of day or elapsed calendar dates.
- Fractional multipliers are allowed; fractional seconds display with at most two decimals.
Frequently asked questions
Can minutes be 75?
Enter 1 hour and 15 minutes instead. Normalized inputs make the result unambiguous.