How do UUIDs store timestamps?

Several UUID versions embed a timestamp directly into their structure. UUID v1, introduced in RFC 4122, encodes a 60-bit Gregorian timestamp representing 100-nanosecond intervals since October 15, 1582. UUID v6 rearranges the same timestamp fields for better sortability, and UUID v7, defined in RFC 9562, stores a 48-bit Unix epoch timestamp in milliseconds. These embedded timestamps make it possible to recover the exact moment a UUID was generated — useful for debugging, auditing, and forensic analysis.

Not every UUID carries time information. Versions 3, 4, and 5 are derived from random data or namespace hashes, so they contain no recoverable timestamp. Version 2 (DCE Security) includes a timestamp but is rarely used in practice.

Tool description

This tool extracts and decodes the timestamp embedded in time-based UUIDs. Paste any UUID and instantly see the encoded date and time in multiple formats: ISO 8601, UTC, local time, and Unix timestamps in both seconds and milliseconds. The tool automatically detects the UUID version and applies the correct decoding algorithm.

Examples

UUID v1 input:

6ba7b810-9dad-11d1-80b4-00c04fd430c8 → April 7, 1998

UUID v7 input:

018f3e88-5c00-7b3a-8512-2d4a3f8e9c01 → May 3, 2024

UUID v4 input (no timestamp):

550e8400-e29b-41d4-a716-446655440000 → "This UUID version does not contain a timestamp"

Features

  • Supports UUID v1 (Gregorian timestamp), v6 (reordered Gregorian), and v7 (Unix epoch milliseconds)
  • Displays results in ISO 8601, UTC, local time, and Unix timestamp formats
  • Automatically detects the UUID version and selects the correct decoding method
  • Validates UUID format before attempting extraction
  • Shows a clear message for UUID versions that do not contain timestamps

How it works

Each time-based UUID version stores its timestamp differently:

  • UUID v1 splits a 60-bit Gregorian timestamp across three fields: time_low (bits 0–31), time_mid (bits 32–47), and time_hi (bits 48–59). The timestamp counts 100-nanosecond intervals since October 15, 1582.
  • UUID v6 reorders the v1 timestamp fields so the most significant bits come first, making UUIDs naturally sortable by creation time while using the same Gregorian epoch.
  • UUID v7 takes a simpler approach: the first 48 bits hold a standard Unix timestamp in milliseconds, making extraction straightforward and compatible with modern systems.

Use cases

  • Debugging distributed systems — determine exactly when a record or event was created by decoding the UUID assigned to it
  • Audit and forensics — verify creation timestamps in databases that use time-based UUIDs as primary keys
  • Migration planning — analyze UUID timestamps to understand data distribution and age before migrating between systems