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Time Duration Calculator

Hours and minutes between two clock times — overnight included — plus adding or subtracting hh:mm durations.

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Reading the times
Calculating the duration
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Result

How long is 9:15 to 17:40? Clock arithmetic is base-60, so quick mental answers are often off by minutes — and an overnight span like 21:00 to 5:00 trips up simple subtraction entirely. This calculator answers both cases exactly.

In the between-times mode, pick a start and an end time and optionally subtract a break in minutes. If the end time is earlier than the start, the calculator assumes the span crosses midnight and adds 24 hours, which is exactly how night shifts are counted.

The add-durations mode takes two amounts of time written as hh:mm — say 7:45 and 6:30 — and adds or subtracts them, carrying minutes correctly. It is the quick way to combine timesheet entries, flight legs, or recording lengths.

Every result is shown three ways — hh:mm, decimal hours, and total minutes — and the whole calculation runs locally in your browser.

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Accepted Formats & Rules

  • Time between two clock times with optional break
  • Add or subtract two hh:mm durations
  • Results in hh:mm, decimal hours, and minutes

Key Benefits

✓ Overnight spans are detected automatically when the end time is earlier than the start.
✓ Every result comes in hh:mm, decimal hours, and total minutes at once.
✓ A second mode adds or subtracts two hh:mm durations without base-60 mistakes.

Use Cases

  • • Find out exactly how long a shift lasts: pick the start and end times, subtract the lunch break, and read the result in hh:mm and decimal hours.
  • • Calculate an overnight span like 9pm to 5am — the calculator adds 24 hours automatically when the end time is earlier than the start.
  • • Add two hh:mm durations, such as timesheet entries or flight legs, with minutes carried correctly instead of decimal guesswork.