Unix Timestamp Converter
Convert between Unix timestamps and human dates in any time zone.
Private by design. Your input never leaves this browser. Conversions run locally on your device.
What this tool handles
- Seconds, milliseconds and microseconds are told apart by digit count, or can be forced.
- Shows ISO 8601, UTC, a chosen time zone, and how long ago the instant is.
- 10 digits is seconds, 13 is milliseconds, 16 is microseconds.
- Converts in both directions: a timestamp to a date, or a date back to a timestamp.
When you would use it
- Reading an epoch out of a log line — Syslog, nginx and most JSON loggers write a bare number rather than a date. Pasting it gives you ISO 8601 in UTC, the same instant in a named zone such as Europe/Prague, and the day of the week.
- A 13-digit value from Date.now() — JavaScript counts in milliseconds, so anything that came out of Date.now() or getTime() has three more digits than a backend timestamp. Both readings are printed either way, so a mismatched unit is obvious.
- Checking a JWT exp or iat claim — Both claims are Unix seconds, so they arrive as ten digits. Paste the raw claim to see when the token was issued or when it lapsed.
- Comparing a database column with wall-clock time — Postgres and several tracing formats emit microsecond epochs of sixteen digits. Typing a date back the other way, such as 2024-05-01 12:00, reads it in the zone chosen under "Time zone" rather than the browser's.
Common questions
Is a Unix timestamp in seconds or milliseconds?
The epoch is defined in seconds, and that is what backends, database columns and JWT claims normally store. Milliseconds are a JavaScript convention; both values are printed on every conversion so you can copy whichever the other system wants.
What unit is an 18-digit number?
Nanoseconds, which is what Go's UnixNano and some tracing pipelines produce. "Interpret numbers as" offers seconds, milliseconds and microseconds for forcing a reading; nanoseconds are reached by auto-detection only.
Which zone is a date without an offset read in?
The one selected under "Time zone", not the machine's. That deliberately differs from Date.parse, which reads "2024-05-01" as UTC but "2024-05-01T12:00" as local time.
Does it handle dates before 1970 and fractional seconds?
Yes to both. A negative number is an instant before the epoch, so -1000000 resolves to 20 December 1969, and 1700000000.5 keeps its half second in the ISO output.
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