How many characters and bytes are in a UUID?

A UUID is 128 bits, or 16 bytes. Its canonical hexadecimal text has 36 characters: 32 hexadecimal digits and four dashes. No dashes gives 32 characters; braces add two more. A 16-character or 16-bit value is not a complete UUID. The output download is a UTF-8 text list, not a binary 16-byte UUID file or a shortened-ID encoding.

Can I generate UUIDs in bulk or download the list?

Use the count buttons for 1, 5, 25, 100 or 1,000 identifiers in v4 or v7. Copy all copies one UUID per line, and Download TXT saves the same formatted list with a final newline. Each row also has its own Copy button. V5 produces one deterministic result for one namespace/name pair; asking for duplicates would not create new identifiers.

What are the odds of a UUID collision?

For independent uniformly random v4 values there are 2^122 possible random-bit combinations. The birthday approximation reaches a 50% chance of a duplicate near 2.7 × 10^18 generated values; no finite batch proves global uniqueness. V7 has a different timestamp/counter/random layout and depends on clock behavior, so the v4 estimate does not describe it. V5 deliberately repeats for the same namespace and name and uses SHA-1, whose collision resistance is not suitable for security-sensitive proof of identity.

Are UUIDs passwords, API secrets or authentication tokens?

Use a purpose-built password or secret generator for those jobs. V4 draws secure randomness, but a UUID is an identifier and does not implement an application’s token lifecycle. V7 exposes its timestamp, v5 is predictable from its inputs, and Nil and Max are fixed constants.

Can I use generated UUIDs in Minecraft resource packs, Bluetooth services or V2Ray?

A v4 UUID can supply an identifier where an application explicitly asks you to create a new UUID, such as a resource-pack manifest or a custom 128-bit Bluetooth service. This page only supplies the identifier: it does not create a manifest, allocate an official Bluetooth 16-bit service ID, configure V2Ray or look up a player’s Minecraft UUID. An existing player identity or offline-player UUID needs that system’s own rules.

UUID v4 Generator

Generate a fresh random UUID v4. This page opens V4 with one identifier; choose a batch of up to 1,000 and copy or download the formatted list. V4 carries no timestamp and has 122 random bits.

Version 4 · randomReady

Version

How many

Format

Validate and inspect a UUID

Check the representation, version and variant. For an RFC v7, read the embedded timestamp. This cannot prove uniqueness, origin or authenticity.

UUID

Formatting, count, version and a valid namespace can be remembered on this device. Names, generated UUIDs and inspection input are not saved. Page presets preserve remembered choices until you explicitly change each setting.

Common questions

How many characters and bytes are in a UUID?: A UUID is 128 bits, or 16 bytes. Its canonical hexadecimal text has 36 characters: 32 hexadecimal digits and four dashes. No dashes gives 32 characters; braces add two more. A 16-character or 16-bit value is not a complete UUID. The output download is a UTF-8 text list, not a binary 16-byte UUID file or a shortened-ID encoding.
Can I generate UUIDs in bulk or download the list?: Use the count buttons for 1, 5, 25, 100 or 1,000 identifiers in v4 or v7. Copy all copies one UUID per line, and Download TXT saves the same formatted list with a final newline. Each row also has its own Copy button. V5 produces one deterministic result for one namespace/name pair; asking for duplicates would not create new identifiers.
What are the odds of a UUID collision?: For independent uniformly random v4 values there are 2^122 possible random-bit combinations. The birthday approximation reaches a 50% chance of a duplicate near 2.7 × 10^18 generated values; no finite batch proves global uniqueness. V7 has a different timestamp/counter/random layout and depends on clock behavior, so the v4 estimate does not describe it. V5 deliberately repeats for the same namespace and name and uses SHA-1, whose collision resistance is not suitable for security-sensitive proof of identity.
Are UUIDs passwords, API secrets or authentication tokens?: Use a purpose-built password or secret generator for those jobs. V4 draws secure randomness, but a UUID is an identifier and does not implement an application’s token lifecycle. V7 exposes its timestamp, v5 is predictable from its inputs, and Nil and Max are fixed constants.
Can I use generated UUIDs in Minecraft resource packs, Bluetooth services or V2Ray?: A v4 UUID can supply an identifier where an application explicitly asks you to create a new UUID, such as a resource-pack manifest or a custom 128-bit Bluetooth service. This page only supplies the identifier: it does not create a manifest, allocate an official Bluetooth 16-bit service ID, configure V2Ray or look up a player’s Minecraft UUID. An existing player identity or offline-player UUID needs that system’s own rules.

UUID v4 uses secure browser randomness. UUID v7 includes the device-clock timestamp, a counter and random bits; clock rollback and other tabs are outside its ordering guarantee. UUID v5 follows the SHA-1 namespace/name construction and is deterministic, not secret. Inspection checks representation and layout, not uniqueness or authenticity.