Unix timestamp converter
Convert between Unix timestamps and human dates, in seconds or milliseconds.
How it works
Converts a Unix timestamp to a readable date and back, handling both seconds and milliseconds, in local time and UTC.
Seconds versus milliseconds is the error that catches everyone. Unix time is defined in seconds since 1 January 1970 UTC, but JavaScript, Java and several databases use milliseconds. A timestamp misread by that factor of a thousand lands in 1970 or in the year 55000, which is at least obvious — the subtle version is a value that is plausible in both, and the tool guesses by magnitude and says which it assumed.
Unix time deliberately ignores leap seconds, so it is not a true count of elapsed seconds. A leap second is represented by the same value repeating, which is why some systems briefly see time run backwards during one.
The 2038 problem is real but narrowing: a signed 32-bit timestamp overflows on 19 January 2038. Most modern systems use 64-bit values, which last about 292 billion years, but embedded and legacy code still carries the limit.
This tool runs entirely in your browser. Nothing you enter is sent to a server, logged or stored, and the page keeps working with the network disconnected.
Common questions
- Is a Unix timestamp in seconds or milliseconds?
- The standard is seconds since 1 January 1970 UTC, but JavaScript and Java use milliseconds. A ten-digit number is seconds; thirteen digits is milliseconds.
- What is the 2038 problem?
- A signed 32-bit timestamp overflows on 19 January 2038. Modern systems use 64-bit values, but embedded and legacy code can still hit it.
- Does Unix time include leap seconds?
- No. It ignores them by definition, so it is not a true elapsed-second count. A leap second repeats a value, which can make time appear to go backwards.
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Sources
- Calculated on this page — At One Place