Time tool
Unix Timestamp Converter
Convert Unix timestamps and dates. View local time, UTC, ISO 8601, seconds, and milliseconds.
Result
Your result will appear here.
How to use Unix Timestamp Converter
- Enter a timestamp or date, choose seconds or milliseconds, and convert.
- Use Now to load the current time.
Example
1700000000Common use cases
- Reading a created_at or expires_at field from an API response that stores time as integer seconds.
- Converting a millisecond timestamp from an application log into a readable date when you need the order of events.
- Checking the exact instant of a JWT iat or exp claim before comparing it with the current time.
Input and output examples
| Input | Output | Notes |
|---|---|---|
1700000000 | 2023-11-14T22:13:20.000Z | Ten digits, read as seconds. |
1700000000000 | 2023-11-14T22:13:20.000Z | Thirteen digits, read as milliseconds. The same instant as the row above. |
Common mistakes to avoid
- Seconds and milliseconds look alike. Ten digits usually mean seconds and thirteen digits usually mean milliseconds. When the value is ambiguous, choose the unit yourself.
- Unix time ignores leap seconds. Every day is counted as exactly 86,400 seconds, so elapsed-time math across a leap second can differ from a clock reading.
- A date without a zone is parsed differently. 2024-01-01 is read as UTC midnight, while 2024-01-01T00:00 without an offset is read as local time, so the same text can give two different instants.
Technical details
Unix time counts seconds from 1970-01-01T00:00:00Z. It follows the POSIX time definition, which does not count leap seconds. In Auto mode the converter reads a number as seconds when its absolute value is below 100,000,000,000 (1e11) and as milliseconds otherwise. ISO 8601 and UTC output are fixed to UTC, while the local date uses your browser’s time zone.
Frequently asked questions
Does the converter account for time zones?
UTC and ISO output do not depend on the time zone. The Local Date value uses your device’s time zone.
Why does a millisecond timestamp show 1972?
Auto mode reads values below 1e11 as seconds. A millisecond value from before 1973-03-03, such as 86400000 (one day), is read as seconds. Choose Milliseconds in the Input unit menu.
Why does the year 2038 matter?
A signed 32-bit integer stores at most 2147483647, which is 2038-01-19T03:14:07Z. Systems that keep time in a 32-bit signed field overflow after that moment.
Are negative timestamps supported?
Yes. Negative values count back from 1970, so -1 is 1969-12-31T23:59:59Z.
Why does my local date differ from a colleague’s?
The Local Date value follows the time zone and locale of the browser that runs the tool. Compare the UTC or ISO 8601 output to get a value that is the same everywhere.