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Time Duration Calculator

Calculate the duration between two times, add or subtract hours and minutes, and convert between hours, minutes and seconds. Free and browser-based.

🕐 Time & Date Tools Free Browser-based

Tool

Start time

End time

End time is on the next day

Time Duration Calculations

This tool handles two common scenarios: finding the gap between two clock times, and adding or subtracting a duration from a given time. Both modes support hours, minutes and seconds and correctly handle midnight crossovers.

Conversion Reference

Unit	Seconds	Minutes
1 minute	60 s	1 min
1 hour	3,600 s	60 min
1 day	86,400 s	1,440 min
1 week	604,800 s	10,080 min

Midnight Crossover

When an end time is earlier than the start time, tick the End time is on the next day checkbox and the calculator adds 24 hours to the end time before computing the difference.

'Can I calculate durations longer than 24 hours?', 'a' => 'Yes. The result shows total hours, minutes and seconds without any 24-hour cap. A duration of 36 hours 30 minutes will show correctly.'], ['q' => 'Is my data uploaded to a server?', 'a' => 'No. Everything runs locally in your browser using JavaScript. Your data never leaves your device.'], ['q' => 'What format should I enter times in?', 'a' => 'Use the time input fields which accept HH:MM or HH:MM:SS format (24-hour clock). The seconds field is optional.'], ]" />