Free Online ISO 8601 Converter

1. Paste an ISO 8601 string into the Parse field to see UTC, local and component forms.
2. Or fill year, month, day, hour, minute, second and ms fields to build a UTC ISO string.
3. Copy the canonical ISO output from the result tile.
4. Watch for the error message if the input isn't valid ISO 8601.

ISO 8601 is the date-time format that ends most ambiguity: 2026-03-15T14:30:00Z is unmistakably 14:30 UTC on the 15th of March 2026. APIs, databases and logging systems prefer it because the string sorts lexicographically into chronological order, and because there's no debate about whether 03/04 is March 4 or April 3.

This tool runs the format both ways. Paste a string — full datetime, date-only, with offset, with fractional seconds, anything the browser's Date constructor accepts — and it shows the parsed UTC ISO form, your local-time rendering and the broken-out year, month, day, hour, minute, second and millisecond components. Or fill the components and it builds the canonical UTC string. Backend engineers debugging API payloads, data analysts cleaning log timestamps and developers generating canonical filenames all use this round-trip.

Useful for debugging API payloads, generating canonical timestamps for filenames and logs, and understanding what an ambiguous datetime in someone else's system actually represents.