ISO 8601 Date & Time Converter

ISO 8601 is the international standard (ISO 8601-1:2019) for representing dates, times, and time intervals. Its most common form is `YYYY-MM-DDTHH:mm:ssZ` — a sortable, unambiguous text representation used by JSON APIs, XML, cloud services and countless programming languages.

This converter renders your date-time in the ISO extended form (`2026-08-13T14:30:00+00:00`), the compact basic form (`20260813T143000Z`), and as an interval (`2026-08-13T14:30:00/2026-08-14T14:30:00`). Paste any recognizable date string and the output updates instantly in UTC or your local timezone.

Timezone:
Enter a date-time above to see the conversion results.

ISO 8601 Date & Time Converter Quick Reference

FormatPattern / DescriptionExample 1Example 2
ISO 8601 (UTC)Standard ISO format2026-08-13T14:30:00Z2026-01-01T00:00:00Z
ISO 8601 Basic20260813T143000Z20260101T000000Z
ISO 8601 IntervalStart/End (+1h)2026-08-13T14:30:00.000Z/P1Y2026-01-01T00:00:00.000Z/P1Y

* Examples are rendered in UTC for the fixed sample instants above.

When to Use ISO 8601 Date & Time

API contracts

JSON REST APIs almost universally exchange ISO 8601 strings. Generate the exact string your contract requires, including `Z` (UTC) or a numeric offset.

Data interchange

Spreadsheets, CSVs and ETL pipelines use ISO 8601 to avoid locale ambiguity (is 07/12 July 12 or December 7?).

Sortable storage

ISO 8601 strings sort lexicographically in the correct chronological order, making them ideal for database keys and log indexing.

Frequently Asked Questions

What is the ISO 8601 date format?

The standard extended form is `YYYY-MM-DDTHH:mm:ssZ`, e.g. `2026-08-13T14:30:00Z`. The `T` separates date from time; `Z` denotes UTC. Offsets like `+08:00` are also valid.

What is the difference between ISO 8601 and RFC 3339?

RFC 3339 is a profile of ISO 8601 restricted to the common `YYYY-MM-DDTHH:mm:ss±HH:MM` form, mandating a timezone. Every RFC 3339 string is valid ISO 8601, but not every ISO 8601 string (e.g. week dates) is RFC 3339.

Should I use Z or an offset like +00:00?

Both mean UTC. `Z` is shorter and more widely understood in JSON APIs; `+00:00` is required by some schemas (e.g. XML Schema `dateTime`). Use the RFC 3339 output to see the offset form.

Does ISO 8601 support milliseconds?

Yes — fractional seconds are optional: `2026-08-13T14:30:00.123Z`. If your input contains milliseconds they are preserved in the output.

Related Time Format Converters

RFC 3339 Date-Time Converter
Convert any date to RFC 3339 format (2026-08-13T14:30:00Z or +00:00 offset). The timestamp standard for JSON APIs and cloud services. Free converter.
ISO Week Date Converter (YYYY-Www-D)
Convert any date to the ISO 8601 week date (year-week-day). See the week number, the ISO year and the weekday for any date. Free online converter.
ISO Ordinal Date Converter (YYYY-DDD)
Convert any date to the ISO 8601 ordinal date: year + day-of-year (e.g. 2026-225). See which day of the year any date is. Free online converter.
Unix Timestamp Converter (Epoch Time)
Free Unix timestamp converter. Convert epoch seconds, milliseconds, microseconds and nanoseconds to human-readable dates instantly. UTC & local time, one click copy.

All Format Guides

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