UUID decoder
Paste a UUID to see what is inside it. The decoder checks the format, names the version and variant, and for time-based UUIDs (v1, v6 and v7) shows when the ID was made. Version 1 and 6 also show their clock sequence and node.
Runs in your browser: nothing you enter is sent anywhere.
How to use it
- Paste a UUID. Upper or lower case, with or without hyphens, in braces or with a urn:uuid: prefix all work.
- Read the version and variant, and for v1, v6 and v7 the time in UTC and in Unix milliseconds.
- Copy the canonical lower-case form or the 128-bit integer if you need them.
How it works
A UUID is 128 bits written as 32 hexadecimal digits. The first digit of the third group is the version; the top bits of the fourth group are the variant (binary 10 for the standard RFC 9562 layout, so 8, 9, a or b).
- v7: the first 12 digits are milliseconds since 1970-01-01 UTC.
- v1: the time is split into three parts stored low first; the decoder puts them back together, subtracts the 1582–1970 gap (122,192,928,000,000,000 intervals of 100 ns) and shows the result.
- v6: the same 60-bit time stored high first.
- v1 and v6 also hold a 14-bit clock sequence and a 48-bit node.
Worked example
017f22e2-79b0-7cc3-98c4-dc0c0c07398f is version 7 (third group starts with 7) with the standard variant (9). Its first 12 digits, 017f22e279b0, are 1,645,557,742,000 in decimal: milliseconds after 1970, which is 2022-02-22T19:22:22.000Z.
The version 1 UUID c232ab00-9414-11ec-b3c8-9f6bdeced846 holds the same moment: 2022-02-22T19:22:22.0000000Z, clock sequence 13256 and node 9f:6b:de:ce:d8:46, whose multicast bit is set, so it is random.
Tips
- Prefer v7 for new database keys: it sorts by creation time and does not expose a MAC address.
- A UUID that fails the check often has a missing or extra digit; count 8-4-4-4-12.
- To make new IDs, use the UUID generator; for Twitter or Discord IDs, the Snowflake ID decoder.
Frequently asked questions
Which UUIDs contain a timestamp?
Versions 1, 6 and 7. Version 1 and 6 count 100-nanosecond intervals since 15 October 1582; version 6 stores the same count in the opposite order so IDs sort by time. Version 7 starts with the Unix time in milliseconds. Version 4 (the most common) is random and has no time.
How do I know the version of a UUID?
It is the first digit of the third group: in 017f22e2-79b0-7cc3-98c4-dc0c0c07398f the third group 7cc3 starts with 7, so it is version 7. The first digit of the fourth group (8, 9, a or b) shows the standard variant.
Can a v1 UUID reveal my computer?
It can. The last 12 digits of a version 1 UUID are often the MAC address of the network card that made it. Generators that avoid this set the multicast bit and use random bits instead; the decoder tells you which case you have.
Is the time exact?
It is the time written by the generator. Version 7 stores milliseconds; versions 1 and 6 store 100-nanosecond steps, shown as seven decimals of a second. Generators may round or shift the clock, so treat it as when the ID was made by that machine's clock.
What is the difference between a UUID and a GUID?
None in practice: GUID is Microsoft's name for the same 128-bit identifier. Old Microsoft GUIDs could use their own variant, which the decoder labels as Microsoft.