Time Duration Calculator

Add & Sum Durations

Enter multiple time durations in HH:MM:SS format and see the running total instantly.

Duration Between Timestamps

Calculate the duration between two timestamps. Enter time-only or full date+time.

How to Use

Adding Durations: Enter time values in HH:MM:SS format (hours, minutes, seconds). For example: 02:30:45 for 2 hours, 30 minutes, and 45 seconds. Click “Add Duration” to include more rows. The total updates automatically as you type.

Between Timestamps: Enter start and end times in either HH:MM:SS format (time-only) or full format YYYY-MM-DD HH:MM:SS (with date). The duration difference calculates instantly.

Conversions: All results display in multiple formats: HH:MM:SS, total seconds, total minutes, total hours, and days with remaining time.

Use Cases

• Video & Media: Sum up video clip lengths to plan playlists or total runtime.
• Work Hours: Track billable hours across multiple tasks or projects.
• Event Planning: Calculate total event duration or time between key moments.
• Fitness: Sum workout session durations to monitor total weekly exercise time.
• Content Creation: Calculate total editing or production time across multiple files.

Frequently Asked Questions

Can I use negative durations?

The calculator works with positive durations. If calculating timestamp duration where end time is before start time, the result will reflect that as a negative span. Ensure start time is earlier than end time for positive results.

What format should I use for timestamps?

Use either HH:MM:SS (time-only) or YYYY-MM-DD HH:MM:SS (full date and time). Both formats are supported. Time-only calculations assume the same date.

Can I convert to other time units?

Yes! Every calculation shows results in seconds, minutes, hours, and a formatted days+hours+minutes breakdown. All conversions update live.

Is my data saved or uploaded anywhere?

No. This tool runs entirely in your browser. All calculations happen locally, and no data is sent to any server.

Can I clear all durations quickly?

Yes, use the “Clear All” button to reset all duration rows at once. You can also remove individual rows with the × button on each row.

What if I enter an invalid time format?

The calculator validates input and will show an error message if the format is incorrect. Ensure times follow HH:MM:SS format where hours, minutes, and seconds are two digits each (e.g., 01:05:09).