Duration Calculator

Duration Calculator

Updated August 20, 2026

Duration calculator online. Find the time between two dates. Free date difference and elapsed time calculator.

Features

  • Difference between two instants as days, hours, minutes, seconds
  • ISO 8601 duration string
  • Millisecond total
  • Accepts Unix or ISO on each side

Common Use Cases

  • Incident length: detect to resolve
  • Token lifetime between iat and exp
  • Build time between CI stamps
  • Age of a file from mtime epoch

Elapsed time, not calendar months

We subtract milliseconds and break the absolute value into days and clock units. We do not emit P1M. For month-aware spans, use the calculator with calendar adds.

Examples

Valid - Two ISOs
2026-01-01T00:00:00Z → 2026-01-02T03:04:05Z

Frequently Asked Questions

Negative durations?

We report the absolute span and which side is later.

Related Tools

ISO 8601

Parse a P… duration

Try it

Convert Time

Unit conversion for a single duration

Try it

Tips

  • Paste JWT iat and exp to see remaining life without the JWT tool.