Unix Timestamp Conversion Tool
Use this Unix timestamp conversion tool to change epoch values into readable dates or calendar dates into Unix time. It reports UTC, local time, ISO 8601 and exact epoch values without uploading input.
Written and checked by TheToolNet Editorial Team · Last reviewed: August 22, 2026 · How we check tools
Classic Unix time counts seconds and does not count leap seconds. A time zone changes the displayed clock time, not the timestamp’s instant.
Convert a Unix timestamp to a date
Use Auto for ordinary current-era values, or choose the unit explicitly when digit length could be ambiguous.
Convert date to Unix timestamp
How to convert a Unix timestamp to a date
- Identify the timestamp unit.
- Scale the value to seconds or milliseconds.
- Add that duration to the Unix epoch, 1970-01-01 00:00:00 UTC.
- Format the resulting instant in UTC or a chosen local time zone.
For example, Unix timestamp 1700000000 seconds is 2023-11-14T22:13:20.000Z. The same instant may show a different date or clock time locally because of the device’s time-zone rules.
Unix seconds, milliseconds, microseconds and nanoseconds
| Unit | Scale | Typical current-era length |
|---|---|---|
| Seconds | 1 second | 10 digits |
| Milliseconds | 10−3 second | 13 digits |
| Microseconds | 10−6 second | 16 digits |
| Nanoseconds | 10−9 second | 19 digits |
Digit-count detection is a convenience, not a universal proof. A far-future seconds value can have as many digits as a present-day milliseconds value. Choose an explicit unit when the source system documents one.
Convert timestamp to Unix time without a time-zone mistake
A numeric Unix timestamp itself has no display time zone. When converting a calendar date to Unix time, however, the entered wall-clock time must be interpreted in some zone. Select UTC if the source includes a Z suffix or explicitly says UTC; select local only when the source means your device’s current zone.
Daylight-saving transitions can make some local clock times nonexistent or ambiguous. This tool rejects a nonexistent local time instead of silently shifting it. An ambiguous fall-back time still depends on the browser’s local-zone rule.
Conversion examples
| Unix seconds | UTC date | Why it matters |
|---|---|---|
| 0 | 1970-01-01 00:00:00 | The Unix epoch |
| −1 | 1969-12-31 23:59:59 | Negative timestamps represent instants before the epoch |
| 2147483647 | 2038-01-19 03:14:07 | Largest signed 32-bit seconds value |
Scope and precision limits
The numeric input accepts signed whole values in seconds, milliseconds, microseconds or nanoseconds. Browser dates have millisecond resolution, so smaller units are retained as input but human-readable output is truncated to whole milliseconds with a visible note. Calendar dates are limited by the browser Date range and its installed time-zone data. This tool follows POSIX-style Unix time and does not count leap seconds.
Frequently asked questions
How do I convert Unix timestamp to date?
Enter the number, select its unit, and convert. The result shows the same instant in ISO 8601 UTC and in your device’s local time.
How do I convert a date to Unix timestamp?
Choose the date and time, state whether that clock reading is local or UTC, then convert. The result includes seconds through nanoseconds.
Is a 13-digit timestamp milliseconds?
For dates near the present, usually yes. Explicit source documentation is more reliable than digit count for unusual historical or future values.
Does changing time zone change Unix time?
No. It changes the human-readable representation of the instant, not the instant’s epoch value.
References and related tools
Planning a recurring calendar milestone? Use the wedding anniversary calculator.