Free Time Duration Calculator Online
Add or subtract two time durations. Enter hours, minutes, and seconds to get instant results.
Key Features
Everything you need in one free tool
Switch between addition and subtraction mode with a single click.
Results update automatically as you type. No button press needed.
All processing is done locally in your browser. Your data stays private.
About This Tool
Quickly add or subtract two time durations given in hours, minutes, and seconds. Results are shown in HH:MM:SS format plus total conversions.
Frequently Asked Questions
How does time addition work?
The tool converts both durations to total seconds, adds them, then converts back to hours, minutes, and seconds.
For example, 1:30:00 plus 0:45:00 gives 2:15:00.
Hours can exceed 23 since this is a duration, not a clock time.
How does time subtraction work?
The tool subtracts the second duration from the first in total seconds.
If the result is negative, it displays as zero.
For example, 2:00:00 minus 0:30:00 gives 1:30:00.
What are the total seconds and minutes for?
These show the result converted to a single unit for easy use in formulas or programming.
For example, 1:30:00 equals 5400 total seconds or 90 total minutes.
Total hours is shown as a decimal, for example 1.5 hours.
Can hours exceed 24?
Yes. This calculator works with durations, not clock times, so hours can be any positive number.
For example, you can add 10 hours + 18 hours to get 28 hours.
This is useful for tracking work hours, video lengths, or any elapsed time.