Duration Calculator
Time & Date · Free Online Tool
Calculate total duration of a time period (hours/minutes/seconds).
Total Duration
0d 04:15:00
15,300 seconds total
Multiple Entries
Add as many durations as you need to sum.
Live Total
The total recalculates instantly as you type.
Day-aware
Days roll into the total without overflow into hours.
How to Use Duration Calculator
- 1Enter the time, date, or value you want to convert.
- 2Select the target format or timezone.
- 3The tool calculates the result instantly.
- 4Copy the converted value for your use.
Features
- ✓100% free — no signup, no subscription, no ads
- ✓Runs entirely in your browser — data never leaves your device
- ✓Fast and lightweight — instant results
- ✓Cross-platform — works on desktop, tablet, and mobile
Frequently Asked Questions
What timezone is used by default?
The Timestamp Converter uses UTC by default but can display results in your local timezone.
Can I convert timestamps from different programming languages?
Yes, the tool supports Unix timestamps (seconds and milliseconds), ISO 8601, and various date string formats.
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Learn the concept
Learn the concept
Understand the programming ideas behind this tool.