UUID Timestamp Decoder
Extract the creation time embedded in a version-1 UUID. (v4 UUIDs are random and carry no time.)
Reviewed by the CalcCafe editorial team · Last updated 1 July 2026 · How we test our tools
Embedded timestamp (UTC)
Relative
Only version-1 (time-based) UUIDs carry a timestamp. v4 UUIDs are random and have none.
How it works
The tool reassembles the 60-bit time field from the UUID, divides by 10,000 to get milliseconds, and subtracts the 1582 Gregorian epoch offset.
Everything is computed locally in your browser — nothing is uploaded.
Frequently asked questions
Which UUIDs contain a time?
Only version-1 (and the related version-2) UUIDs embed a timestamp — 100-nanosecond intervals since 1582-10-15. Version-4 UUIDs are fully random and have no time.
How accurate is it?
The embedded clock is precise to 100 nanoseconds; this tool shows it to the millisecond.
People also ask
How do I create a UUID based on a timestamp?
Use a library that generates version 1 or version 7 UUIDs, since those are the time-based variants. In Node, the uuid package offers v1() and v7(); in Python, uuid.uuid1() produces a v1 value, and Python 3.14 and later add uuid.uuid7(). v1 embeds a 100-nanosecond count since 1582 plus a node identifier, while v7 puts a 48-bit Unix millisecond timestamp in the leading bits followed by random data, which is the better choice for new systems.
Can I decode UUID?
Only partially, and only for some versions. A v1 UUID can be decoded into its creation time, a 14-bit clock sequence, and a 48-bit node field that is often the generating machine's MAC address, which is exactly what this tool extracts. A v7 UUID reveals its creation time in the first 48 bits, while v4 UUIDs are random apart from the version and variant bits and contain nothing to decode.
Has a UUID collision ever happened?
Collisions by pure chance are effectively impossible: a v4 UUID has 122 random bits, so you would need to generate about 2.7 quintillion of them to reach a 50 percent chance of a single duplicate. Real-world collisions do occur, but they come from bugs, such as a poorly seeded random number generator, a virtual machine cloned along with its RNG state, or v1 UUIDs generated with a duplicated node ID and clock. Using a cryptographically secure generator, like crypto.randomUUID(), avoids the known failure modes.
Is UUID v7 time-ordered?
Yes. The first 48 bits of a v7 UUID hold the Unix timestamp in milliseconds, so UUIDs generated later sort after earlier ones when compared as strings or bytes. Within the same millisecond the ordering falls back to the random bits, unless the generator uses the optional monotonic counter defined in RFC 9562 to keep even those ordered.
Should I use UUID v4 or v7?
Use v7 when the UUID will be a database primary key or an index key, because its time-ordered prefix keeps inserts clustered and B-tree indexes compact, whereas random v4 keys scatter across the index. Use v4 when you do not want to reveal when a record was created, for example in public tokens or share links, since the timestamp in a v7 value is trivially readable. Both are 128 bits and equally unlikely to collide.
How to get timestamp from UUID v7?
Take the first 12 hexadecimal characters (the first 48 bits) and parse them as a big-endian integer; the result is Unix time in milliseconds. In JavaScript: const ms = parseInt(uuid.replace(/-/g, '').slice(0, 12), 16); then new Date(ms) gives the creation time. For example a v7 UUID starting 018f-... decodes to a timestamp in 2024.
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Sources & references
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