Time Calculator
Add or subtract times, and compute the difference between two times in hours, minutes and seconds.
How to use the Time Calculator
- Enter your inputs into the Time Calculator above.
- Results update instantly as you type — no submit button needed.
- Adjust any value to see how the result changes in real time.
The time arithmetic
Sum: convert to seconds, add, convert back · · · Difference: subtract one from the other; handle midnight wrap-around if needed
All times are reduced to seconds for arithmetic, then converted back to HH:MM:SS. Cross-midnight differences should specify whether they wrap forward (next day) or backward (yesterday).
Worked example
2:30:00 + 1:45:30 = 4:15:30. Time between 9:15 AM and 5:30 PM: 8 hours 15 minutes. From 10:30 PM to 6:00 AM (cross midnight): 7 hours 30 minutes.
Frequently asked questions
Does this handle 12-hour vs 24-hour?
Yes. Input can be either AM/PM or 24-hour. Internally everything is converted to a single representation; output respects your preferred display format.
What about seconds?
Seconds are supported. For most everyday use (commute time, workout duration), HH:MM suffices; seconds matter for sports timing and scientific applications.
Does this support negative times?
Yes — subtraction can produce negative durations. Useful for representing "10 minutes early" or comparing actual vs. expected times.