DEVELOPER

Date Format Converter

Paste a date in almost any common format and get it converted to every other format at once.

One input, every format

Paste a date as a Unix timestamp, an ISO 8601 string, an RFC 3339 string, or an RFC 2822 string (the format used in email headers, such as Mon, 21 Sep 2026 14:13:20 +0000), and this tool detects which format it is and shows the same instant in all of the others: ISO 8601, UTC, local time, Unix seconds, Unix milliseconds, RFC 2822 and RFC 3339.

When the format is ambiguous

An ISO-style string without a UTC offset (like 2026-09-20T12:30:00, with no Z or +hh:mm) does not specify a time zone by itself. This tool reads it as UTC and says so, since that is the safest default; convert with the ISO 8601 Converter directly if you need to assume a different zone.

Want the background? Read our comprehensive guide: ISO 8601 Date and Time Format.

How to use this tool

Paste a date in any of the supported formats.
Select Detect and convert.
Read the same instant shown in every supported format.
Copy the one you need.

Examples

One RFC 2822 date, shown in every other supported format.

Detected as RFC 2822

Mon, 21 Sep 2026 14:13:20 +0000

ISO 8601: 2026-09-21T14:13:20.000Z
RFC 3339: 2026-09-21T14:13:20Z
Unix seconds: 1790000000

Detected from a Unix timestamp

1790000000 (seconds)

RFC 2822: 2026-09-21T14:13:20.000Z

Detected from an ISO 8601 date

2026-09-20

Unix seconds: 1789862400

Frequently Asked Questions

Which formats are detected automatically?

Unix timestamps in seconds or milliseconds, ISO 8601, RFC 3339 and RFC 2822 (email-style) dates are all detected from the text you paste, with no need to say which one it is.

What is the difference between ISO 8601 and RFC 3339?

RFC 3339 is a stricter, internet-focused profile of ISO 8601: it always requires a full date, a full time and an offset or Z. Most APIs that mention ISO 8601 actually follow the RFC 3339 profile.

What is RFC 2822 used for?

It is the date format used in email and HTTP headers, for example Mon, 21 Sep 2026 14:13:20 +0000. This tool both reads and produces it.

My date was not recognised. What should I do?

Check for typos in the month name or a missing time zone offset. If you know which exact format you have, the ISO 8601 Converter or RFC 3339 Converter may give a more specific error.