Convert any date and time into a valid RFC 3339 formatted timestamp — or decode an existing RFC 3339 string back into its components. Enter a date, time, and timezone offset, choose whether to include milliseconds or use the Z suffix for UTC, and get your formatted timestamp along with equivalent ISO 8601, RFC 2822, and Unix timestamp representations.
RFC 3339 Timestamp
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ISO 8601
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RFC 2822
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Unix Timestamp (seconds)
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Unix Timestamp (milliseconds)
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RFC 3339 is an internet standard (defined by the IETF) for representing date and time in text, commonly used in APIs, HTTP headers, and JSON data. It is a strict profile of ISO 8601, meaning every valid RFC 3339 timestamp is also ISO 8601 compliant, but RFC 3339 requires a timezone offset (or 'Z' for UTC) and prohibits some of the optional variations allowed by ISO 8601.
'Z' stands for Zulu time, which is the military designation for UTC (Coordinated Universal Time). In RFC 3339, '2026-03-10T13:00:00Z' and '2026-03-10T13:00:00+00:00' are equivalent — both represent the same moment in UTC. The 'Z' form is more compact and widely used in modern APIs.
RFC 3339 timestamps are unambiguous — they always include a timezone offset, so there's no confusion about which part of the world a time refers to. They are human-readable, sortable as plain strings, and universally supported across programming languages and platforms, making them ideal for data interchange.
A Unix timestamp counts the number of seconds (or milliseconds) elapsed since January 1, 1970 at 00:00:00 UTC. It is a purely numeric representation of a moment in time. RFC 3339, by contrast, is a human-readable text format. Both refer to the same underlying point in time — this tool shows you both representations simultaneously.
It depends on your use case. Many systems only need second-level precision, so milliseconds can be omitted. However, if you're logging events, measuring performance, or working with high-frequency data, including milliseconds (e.g. '2026-03-10T13:00:00.547+00:00') provides finer accuracy. RFC 3339 supports both forms.
January 19, 2038 is significant for 32-bit Unix timestamps, which will overflow (the 'Year 2038 problem'). RFC 3339 itself as a text format is not affected by this limit — it can represent dates far beyond 2038. However, software or databases that store timestamps as 32-bit signed integers may encounter issues, which is why modern systems use 64-bit integers.
Select your local date and time, then choose your local timezone offset from the dropdown. The converter will build the RFC 3339 string using that offset (e.g. '2026-03-10T08:00:00-05:00' for Eastern Standard Time). If you need a UTC timestamp, select UTC and optionally enable the 'Z' suffix option.
RFC 2822 is an older date-time format used primarily in email headers (e.g. 'Tue, 10 Mar 2026 13:00:00 +0000'). It is human-readable but less compact than RFC 3339. Modern APIs overwhelmingly prefer RFC 3339/ISO 8601, but RFC 2822 is still relevant for email systems and some legacy web protocols.