Unix Timestamp Converter
How to use unix timestamp converter
- Choose timestamp-to-date or UTC-date-to-timestamp mode.
- Select seconds or milliseconds for a numerical timestamp.
- Calculate and keep the UTC ISO string with the unit label.
Convert Unix seconds or milliseconds to an exact UTC date-time, or convert a UTC date-time to a timestamp.
How the result is calculated
The calculator validates the required dates, units and range before producing a result. Keep the inputs and the selected convention with the output so another person can reproduce it.
Read all calculation conventionsHow to read your result
Keep the inputs and conventions beside the answer. These values explain what the result measures.
| Result field | Meaning |
|---|---|
| UTC ISO output | An exact UTC date-time in the browser’s millisecond time model. |
| Unix seconds | Seconds from the 1970 UTC epoch; fractional values retain millisecond precision. |
| Unix milliseconds | The same instant at a scale 1,000 times larger. |
The epoch is one exact UTC instant
A timestamp of zero represents January 1, 1970 at 00:00 UTC. A value of 1,000 milliseconds represents one second after that instant.
Try the example in the calculator above. Change one input at a time and compare the target, interval and selected rules. For a longer explanation read Unix Timestamps vs Calendar Dates: Units, UTC and Conversion.
Conventions to keep with your result
This uses the browser’s ECMAScript time model without leap-second representation. Negative timestamps identify dates before the epoch. A date-only birthday does not imply a known exact birth instant.
Unix Timestamp Converter: frequently asked questions
Why do seconds and milliseconds give different dates?
Their scale differs by 1,000. Choose the unit explicitly.
Can timestamps be negative?
Yes. They represent instants before January 1, 1970 UTC.
Does changing the output zone change the timestamp?
No. A timestamp identifies an instant; a zone changes its local display.
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