How to use this tool
Choose duration addition, duration subtraction or elapsed clock time first.
Enter durations as hours:minutes[:seconds]. Elapsed clock times use a 24-hour clock; an earlier end means the following day.
Convert to seconds, add or subtract, then format as hours:minutes:seconds
Worked example
2:15:00 · hours : minutes : seconds
Fixed example using the settings below. Monetary examples use USD; dates and times use their stated reference values. This example stays unchanged when you edit your calculation.
Example inputs
- Calculation: Add durations
- First duration: 1:30
- Second duration: 0:45
Method illustration: 1:30 + 0:45 = 2:15:00, or 2.25 hours. From 22:00 to 06:00 is 8 hours overnight.
Assumptions and limits
- Duration hours can exceed 24. Minutes and seconds must be between 00 and 59.
- Elapsed mode accepts clock times from 00:00 to 23:59 and spans less than 24 hours. Identical times mean zero elapsed time.
- No time zones or daylight-saving adjustments are applied.
Check or report a result
Check the units, selected calculation and assumptions first. Compare the fixed example above with your inputs to identify what changed.
Report a calculation issue with the page address, hypothetical inputs, result displayed and result expected. Do not include passwords, bank details or other private information.