Unix Timestamp Converter
Converts between Unix time and a readable UTC date, in both directions.
Results
What this tool does
Unix time is a single number counting seconds since the first instant of 1970, and it is how nearly every computer stores a moment internally — in logs, in databases, in APIs, in file metadata. It has no time zone and no daylight saving, which is exactly why it is used, and exactly why it is unreadable. The conversion here is done with pure calendar arithmetic rather than a date library, so the same number gives the same answer everywhere.
Formula
seconds since 1 January 1970 in UTC, converted by calendar arithmetic
Variables
| Symbol | Meaning | Unit |
|---|---|---|
text | Timestamp or date | — |
mode | Direction | — |
OUT | Date and time in UTC | — |
DT | Date | — |
TM | Time | — |
WD | Day of the week | — |
SE | Seconds since 1970 | — |
MS | Milliseconds since 1970 | — |
Worked example
- Timestamp or date1758240000
- Directionto_date
- Date and time in UTC2025-09-19T00:00:00Z
- Date2025-09-19
- Time00:00:00
- Day of the weekFriday
- Seconds since 19701758240000
- Milliseconds since 19701758240000000
Limitations
- The calculation runs entirely in your browser. The values you type are never sent to a server.
- Dates are handled as calendar dates. Time zones, daylight saving changes and public holidays are not taken into account.
Frequently asked questions
Seconds or milliseconds?
It works it out from the length. A timestamp in seconds for any date between 2001 and 2286 has ten digits; the same moment in milliseconds has thirteen. Anything longer than eleven digits is therefore read as milliseconds, which covers every practical case and is the same rule most libraries use. Unix time counts in UTC and ignores leap seconds, so the conversion is pure arithmetic with no time zone anywhere in it.