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Time Calculator

Add or subtract a duration from a clock time and see whether the result moves to another day.

Starting time
Result9:30 AM.The adjusted clock time includes a clear previous-day or following-day indicator.

Calculations happen locally in your browser.

How to use this calculator

  1. Enter a starting time, choose add or subtract, then enter duration hours and minutes.
  2. Review the live result and use Copy result when you need to share it.

How the calculation works

The selected AM/PM time is converted to minutes after midnight, the duration is applied, and the result is displayed in 12-hour time while retaining its day offset.

Formula

Result = starting time ± duration

Step-by-step calculation

  1. Enter a starting time, choose add or subtract, then enter duration hours and minutes.
  2. The selected AM/PM time is converted to minutes after midnight, the duration is applied, and the result is displayed in 12-hour time while retaining its day offset.
  3. Check the displayed result, then copy it if needed.

Worked example

Adding 1 hour 30 minutes to 11:30 PM produces 1:00 AM on the following day.

Risk guidance

Frequently asked questions

Can the result cross midnight?

Yes. The result identifies how many days earlier or later the adjusted time falls.

Does this tool send my inputs anywhere?

No. The interactive calculation runs in your browser and this site does not submit tool inputs to a backend.

How should I use the result?

Check that the entered units and values match your situation, especially around dates, breaks, and rounding.

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