Free online calculator

Time Calculator

Calculate the duration between two times or add and subtract hours, minutes and seconds with overnight support.

✓ Instant results✓ No sign-up✓ Runs in your browser
How it works

Formula and method

Duration = end time − start time. If overnight is enabled and the result is negative, 24 hours are added.

Worked example

From 9:15 AM to 5:45 PM is 8 hours 30 minutes.

Assumptions

  • Times are on the same date unless overnight is enabled.
  • A day contains 24 hours.

Reference sources

Reviewed and updated 2026-07-14

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