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WorkHoursKit

Time Duration Calculator

Find elapsed time between two clock times, including a period that crosses midnight.

Elapsed time Overnight support Decimal hours Total minutes
Privacy: calculations are completed in your browser. The calculator does not require an account or send the entered values to a WorkHoursKit database.

How to use the Time Duration Calculator

  1. Enter the start time and end time.
  2. Review the values before calculating, especially which calendar day the end time belongs to.
  3. Select Calculate to measure elapsed hours and minutes, including a period that crosses midnight.
  4. Correct the inputs if the result looks unexpected; a common source of error is treating an overnight end time as earlier on the same calendar day.

What this calculator does

Find elapsed time between two clock times, including a period that crosses midnight. Only the values entered on the page are used to measure elapsed hours and minutes, including a period that crosses midnight.

This calculator processes the entered time values in the browser and presents both a readable duration and, where relevant, a decimal-hour value. Keep source records such as approved punches or timesheets when the result will be used for payroll review.

Duration = end time - start time. When the end is earlier, it is treated as the following day.

Why crossing midnight changes the duration

A clock time does not include a date. When the end time is earlier than the start time, this calculator treats the end as occurring on the following day. That convention is useful for overnight work, but it should not be used when the two times actually belong to unrelated dates.

Calculation example

Example input: Start 8:15 AM; End 5:45 PM

Example result: 9h 30m, 9.50 decimal hours, or 570 minutes.

Your result will change with the start time and end time; check which calendar day the end time belongs to before comparing it with another system.

How to interpret the result

Time entries can cross midnight when the calculator supports an end time earlier than the start. Review breaks carefully and avoid entering the same unpaid period twice.

In particular, confirm which calendar day the end time belongs to and avoid treating an overnight end time as earlier on the same calendar day.

Practical checks before using the result

  • Verify the key assumption: which calendar day the end time belongs to.
  • Avoid a common error: treating an overnight end time as earlier on the same calendar day.

Calculation design and testing notes are documented in the Calculator Methodology and Accuracy Policy.

Related WorkHoursKit tools

Overnight Shift Calculator Calculate a shift that begins on one day and ends on the next day. Split Shift Calculator Combine up to three separate work periods without counting the gaps between them. Minutes to Decimal Hours Convert a total number of minutes into payroll-friendly decimal hours. Decimal Hours to Time Change a decimal-hour value into a familiar hours-and-minutes duration.
Important: verify source information, official requirements and workplace policies before using a result for payroll, compliance, scheduling, staffing or employment decisions.