Unix timestamp converter
Convert between timestamps and dates in both directions, with automatic seconds or milliseconds detection.
Current timestamp
LiveTimestamp → date
Date → timestamp
2025-01-01 12:00:00 and similar, parsed in your local time zone.Common reference timestamps
How Unix time works
A Unix timestamp (also called epoch time or POSIX time) counts the number of seconds elapsed since 00:00:00 UTC on 1 January 1970, ignoring leap seconds. It is a single number, it sorts correctly, and it carries no time zone — which is exactly why it is the standard way to store an instant in databases, logs and APIs.
The ambiguity is only in the unit. Seconds give a 10-digit number; milliseconds give 13. Mixing them produces a date in 1970 or in the year 55,000, so this converter reports which unit it detected rather than guessing silently.
Displaying a timestamp is a separate step: the same instant is a different wall-clock time in every time zone. That is why the result shows local time and UTC side by side. When you are debugging a discrepancy, compare UTC values first — if UTC matches, the data is right and only the display time zone differs.
Two practical gotchas. Leap seconds are not counted, so Unix time and UTC drift by a small integer number of seconds that is handled by the clock, not by the timestamp. And the famous 2038 problem only affects software storing the value in a signed 32-bit integer; 64-bit storage and JavaScript numbers are fine.
For storage, prefer UTC timestamps with an explicit ISO 8601 string when humans need to read it (2025-01-01T12:00:00Z). The trailing Z is what prevents the most common bug: a timestamp silently interpreted in the wrong zone.
Frequently asked questions
Seconds or milliseconds — which do I have?
Seconds timestamps have 10 digits, milliseconds have 13. This converter detects both automatically and tells you which it assumed.
Why does the converted time differ from what I expect?
Unix timestamps are absolute — they count seconds since 1 January 1970 UTC. What differs is the time zone used to display them, so the same timestamp is a different wall-clock time in each zone.
What happens in 2038?
Systems that store a Unix timestamp in a signed 32-bit integer overflow on 19 January 2038. Modern 64-bit systems and JavaScript numbers are unaffected.