Universally unique identifier
A universally unique identifier is a standardised alphanumeric code used to distinguish information or objects in computer systems.
How big is it?
16 B · identifier size
Identifier size · standard
A little perspective
Universally unique identifier vs IPv6 address: data size comparison
The identifier size of a universally unique identifier is approximately equal to the address size of an IPv6 address.
BYTES OF DATA
A universally unique identifier is a standardised alphanumeric code used to distinguish information or objects in computer systems.
An IPv6 address is a numerical label used to identify devices on a computer network using the Internet Protocol version 6.
Measurements, assumptions & sources +
Universally unique identifier
Identifier size: 16 B; standard.
A UUID is a standardized 128-bit identifier. Its conventional hyphenated text form is 36 characters, not 16 bytes of displayed text.
RFC 9562 defines a UUID as 128 bits, equivalent to 16 bytes; the standard hyphenated text representation is 36 characters.
RFC 9562 — Universally Unique IDentifiers (UUIDs)
The marked identifier size is calibrated. Unmeasured illustration details are representative.
IPv6 address
Address size: 16 B; standard.
An IPv6 address is a protocol-defined 128-bit identifier (16 bytes), not a claim about a network prefix or its displayed text length.
RFC 4291 specifies IPv6 addresses as 128-bit identifiers, equivalent to 16 bytes; the textual notation is not this byte count.
RFC 4291 — IP Version 6 Addressing Architecture
The marked address size is calibrated. Unmeasured illustration details are representative.
Use the visual comparison to explore its scale, then check the measurements and sources.
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Why this measurement?
Why we use 16 B
We compare the identifier size of a universally unique identifier. This value follows a stated standard.
A UUID is a standardized 128-bit identifier. Its conventional hyphenated text form is 36 characters, not 16 bytes of displayed text.
RFC 9562 defines a UUID as 128 bits, equivalent to 16 bytes; the standard hyphenated text representation is 36 characters.
The picture identifies the subject; the diagram compares the recorded values. How calibrated comparisons work →
Recorded properties
Dimensions and measurements
| Property | Selected value | Recorded range | Basis |
|---|---|---|---|
| 16 B | Not recorded | standard |
Around this scale
Explore nearby values.
Compare examples with lower, similar and higher values. Each card names the measurement being compared.
Nearest lower valueDigital informationEthernet MAC address6 BAddress sizeAn Ethernet MAC address is a unique identifier assigned to network interfaces for communications on physical networks.Around the same scaleDigital informationIPv6 address16 BAddress sizeAn IPv6 address is a numerical label used to identify devices on a computer network using the Internet Protocol version 6.Nearest higher valueDigital informationSHA-256 digest32 BBinary digest sizeA SHA-256 digest is a unique digital fingerprint generated from input data using the SHA-256 cryptographic hash algorithm.Sources and method
Want to check the number?
The source records and measurement method remain available for inspection.
- RFC 9562 — Universally Unique IDentifiers (UUIDs)IETF standards-track specification stating that a UUID is 128 bits long.
There’s always another scale
Follow your curiosity.
DigitalIPv6 address16 BAn IPv6 address is a numerical label used to identify devices on a computer network using the Internet Protocol version 6.DigitalSHA-256 digest32 BA SHA-256 digest is a unique digital fingerprint generated from input data using the SHA-256 cryptographic hash algorithm.DigitalGPS navigation message subframe37.5 BA GPS navigation message subframe is a segment of digital data transmitted by GPS satellites to provide positioning and timing information to receivers.
DigitalASCII character1 BAn ASCII character is a letter, digit, punctuation mark or control code encoded using the American Standard Code for Information Interchange.DigitalEthernet MAC address6 BAn Ethernet MAC address is a unique identifier assigned to network interfaces for communications on physical networks.DigitalIPv4 address4 BAn IPv4 address is a numerical label used to identify a device on a computer network that uses Internet Protocol version 4 for communication.DigitalEd25519 digital signature64 BAn Ed25519 digital signature is a cryptographic value used to verify the authenticity and integrity of digital messages or documents.DigitalBitcoin block header80 BA Bitcoin block header is a fixed-format data structure containing summary information about a block in the Bitcoin blockchain.