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Time Duration Calculator

Duration between two times with automatic overnight span handling.

Duration between two times

How it works

  1. Both times are parsed strictly as 24-hour wall times; the duration is the difference of the two in seconds: pure elapsed time with no time zones or DST involved.
  2. If the end time is not later than the start time, the span is treated as crossing midnight (+24 h) and the result is explicitly labeled as an overnight span (22:00→06:00 is 8 hours).
  3. The same duration is shown three ways (H:MM:SS, total minutes, and decimal hours) because timesheets, invoices, and calendars each expect a different format.

Good to know

  • Start and end on the same wall clock (22:00 → 22:00) count as 24 hours under the overnight rule; the label makes that visible.
  • Optional seconds are supported: 09:15:30 → 17:00 keeps the 30 seconds in every figure.
  • For spans that involve calendar dates and zones, use the date difference tools instead; they handle DST properly.
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Frequently asked questions

How does it handle an overnight span?
If the end time is not later than the start time, the tool adds 24 hours and marks the result as an overnight span: 22:00 to 06:00 is 8 hours.
Is this duration or clock arithmetic?
Duration. It measures elapsed time between two wall-clock times on the assumption they are on consecutive calendar days when the span crosses midnight.
Why no dates or time zones here?
Keeping it time-only makes the common case (shift spans, meeting lengths) instant. For date-and-zone-aware spans, use the Date Difference tools, which handle DST properly.