About the ISO 8601 Date Formatter
Paste a date in almost any form — a Unix timestamp, "2024-01-01", "March 5 2026 14:00", an RFC 2822 email date — and get it back in the standard formats developers actually need: full ISO 8601 in UTC, date-only ISO, ISO with your local offset, RFC 2822 for HTTP headers and email, and your locale's human-readable string. Click any result to copy it.
Why ISO 8601 is the format to standardise on
ISO 8601 writes dates from the largest unit to the smallest — 2026-03-05T14:00:00.000Z — which means alphabetical order is chronological order, there is no ambiguity between day-first and month-first conventions, and the trailing Z (or an explicit +02:00 offset) states the time zone unambiguously. It is the native format of JavaScript's Date.toISOString(), JSON APIs, databases, log files and most modern standards including RFC 3339, which is a slightly stricter profile of ISO 8601 used on the web.
The output formats explained
- ISO 8601 (Full) — 2026-03-05T14:00:00.000Z; UTC with milliseconds. Use for APIs, databases and logs.
- ISO 8601 (YMD) — 2026-03-05; the date part only, ideal for file names, sorting and date-only fields.
- Local ISO — the same instant expressed in your computer's time zone, useful for datetime-local inputs.
- Localized String — what your operating system's locale would display, for checking how users will read it.
- Short Date — the locale's compact date form.
- RFC 2822 / UTC — Thu, 05 Mar 2026 14:00:00 GMT; the format required in HTTP Date headers, cookies and email.
Input tips
- Unix timestamps in seconds (1704067200) and milliseconds (1704067200000) are both accepted.
- Any string JavaScript's Date can parse works — ISO strings, RFC 2822 strings and most natural formats such as "Jan 5, 2026 10:30".
- Dates without a time zone are interpreted in your local zone; append Z to force UTC.
- Click Now to load the current instant and see it in every format at once.
How to use the ISO 8601 Date Formatter
- 1Enter a date. Type or paste a date string or Unix timestamp, or click Now for the current time.
- 2Read the formats. Every supported format is generated instantly in its own card.
- 3Copy. Click a card to copy that representation to your clipboard.
Frequently asked questions
- What does the Z at the end of an ISO date mean?
- Z stands for Zulu time — UTC. It tells the reader the timestamp has no local offset applied. An offset such as +05:30 can appear in its place.
- What is the difference between ISO 8601 and RFC 3339?
- RFC 3339 is a profile of ISO 8601 for internet timestamps: it requires the full date and time with an explicit offset or Z, and allows a space instead of T. Any RFC 3339 string is valid ISO 8601.
- How do I convert an ISO date back to a Unix timestamp?
- Use the Timestamp Converter tool, which converts in both directions and shows seconds and milliseconds.
- Why does my date show a different day in Local ISO than in ISO 8601?
- Because your time zone is ahead of or behind UTC. 2026-03-05T23:30Z is already 6 March in time zones east of UTC+0:30 — both values represent the same instant.