Home/Glossary/Unix Timestamp

Unix Timestamp

The number of seconds elapsed since January 1, 1970 00:00:00 UTC (the Unix epoch).

DevelopmentAlso called: "epoch time", "posix time"

Unix timestamps provide a universal, timezone-independent way to represent time.

Key characteristics

  • Integer count of seconds (or milliseconds in some systems).
  • Always in UTC (no timezone offset).
  • Same value globally at any given moment.
  • Easy arithmetic for time calculations.

Common formats

  • Seconds: 1609459200 (10 digits).
  • Milliseconds: 1609459200000 (13 digits, JavaScript).
  • Microseconds: Used in high-precision systems.

Use cases

  • Database timestamp storage.
  • API response timestamps.
  • Log file entries.
  • Cache expiration times.

Gotchas

  • Year 2038 problem (32-bit signed integer overflow).
  • Leap seconds not accounted for.
  • Conversion errors between seconds/milliseconds.