Developer · free local utility
Translate Unix seconds or milliseconds into readable dates, or convert an ISO date back into both timestamp units.
Enter a numeric Unix timestamp or an ISO 8601 date. Values below one trillion are interpreted as seconds.
Timezone names and ambiguous human date formats are not inferred. Prefer explicit ISO 8601 input with a timezone offset.
Always verify the result in the system where you will use it. The page intentionally avoids accounts, uploads, and claims that go beyond the calculation it performs.
Absolute numeric values below 1,000,000,000,000 are treated as seconds; larger values are treated as milliseconds.
Each browser formats local time using the device timezone and locale configuration.
Use ISO 8601 with an explicit Z or offset, such as 2026-07-15T09:00:00+08:00, to avoid timezone ambiguity.