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Duration Calculator

Add or subtract durations in HH:MM:SS format, including values longer than 24 hours and negative results.

Convert in your browser · No sign-up

Minutes and seconds must be 00–59. This adds durations, not clock times or time zones; hours support up to 12 digits.

Up to 100,000 UTF-16 units per input and 1,000,000 per result. See the supported formats and examples below.

Result

Add your input or load an example, then run the tool. Your result will appear here.

How to use

  1. Add or subtract durations in HH:MM:SS format, including values longer than 24 hours and negative results.
  2. Choose the mode or options, then run the tool.
  3. Review the result, then copy or download the TXT file.

Example

01:30:00 + 00:45:30 = 02:15:30

Details and limitations

Text stays in your browser; it is not sent to a conversion server.

Format references

Tool page updated: