Time Utility

Time Duration Calculator

Determine the exact duration between two dates and times down to hours, minutes, and seconds.

Start Date

Start Time

End Date

End Time

Enter valid parameters to compute duration.

Time Math

How to Calculate
Time Duration

Calculating time duration is the process of finding the elapsed time between a starting event and an ending event.

Converting times to 24-hour military format simplifies subtraction and prevents errors when calculations span PM to AM hours.

Calculations crossing midnight are resolved by adding 24 hours to the end time before performing standard subtraction.

Subtract minutes first. If the end minutes are less than start minutes, borrow 60 minutes from the hours column.

To calculate duration manually, it is easiest to convert standard 12-hour clock times (AM/PM) into 24-hour military format:

AM times: Keep the hour exactly the same (except 12:00 AM, which becomes 00:00).
PM times: Add 12 to the hour (except 12:00 PM, which stays 12:00).