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Duration Formatter

Parse and format time durations. Convert ISO 8601 durations, milliseconds to human-readable, and between time units (ms, seconds, minutes, hours, days, weeks, months, years). Runs entirely in your browser — your data never leaves your machine.

duration time iso8601 milliseconds converter formatter

Published May 30, 2026

All interactive tools run entirely in your browser. Your data never leaves your device.

How It Works

Enter an ISO 8601 duration string (like P1Y2M3DT4H5M6S) or a millisecond value and get a full breakdown into years, months, weeks, days, hours, minutes, seconds, and milliseconds. You can also convert between any two time units directly.

Features

  • Parse ISO 8601: full support for P[nY][nM][nW][nD][T[nH][nM][nS]] format
  • Parse milliseconds: break down any millisecond value into components
  • Unit conversion: convert between 8 time units (ms, sec, min, hr, day, wk, mo, yr)
  • Human-readable output: formatted duration string with proper pluralization
  • ISO output: generates valid ISO 8601 duration strings
  • Total milliseconds: always shows the total duration in ms
  • Component breakdown: shows each non-zero time component
  • 6 examples: ISO durations, millisecond values, and conversions
  • Private: runs entirely in the browser — no data transmitted

Use Cases

  • Converting API response times (ms) to human-readable durations
  • Parsing ISO 8601 durations from JSON/XML data
  • Calculating time differences for scheduling
  • Converting between time units for configuration values
  • Understanding duration values in logs and metrics