Unix Timestamp Converter

1. Choose Timestamp → date to turn epoch seconds or milliseconds into a readable date.
2. Choose Date → timestamp to turn a date from the picker into Unix seconds and milliseconds.
3. Use Auto-detect, or pick Seconds or Milliseconds explicitly for ambiguous values.
4. Select Now at any time to fill in the current moment, then copy any row.

Conversion runs entirely in your browser and is never sent to FKINFAST servers. Nothing you enter is stored, logged or shared.

Unix time (also called epoch time or POSIX time) is the number of seconds that have elapsed since 1 January 1970 at 00:00:00 UTC, not counting leap seconds. It is timezone-free: the same instant is the same timestamp everywhere, and only the display changes when you render it in local time.

• Values before 1970 are negative integers, for example -86400 is 31 December 1969.
• JavaScript, Java and many databases store timestamps in milliseconds, while Unix commands, PHP and most APIs use seconds.
• This converter supports the full range of JavaScript dates, roughly ±8.64 × 10¹⁵ milliseconds around the epoch.

Both are Unix time, just with a different scale. Auto-detect uses the digit count as a practical rule: ten digits or fewer (below 100,000,000,000) are seconds, 11 digits or more are milliseconds. That covers dates until the year 5138 in seconds and keeps millisecond values unambiguous.

The result panel always shows UTC and your browser's local time side by side. The date picker has no timezone of its own, so it is interpreted as local time. If you need a specific offset, type or paste an ISO 8601 value ending in Z for UTC or with an offset such as +02:00.

When converting the other way, both Unix seconds and milliseconds are UTC-based, so the same moment produces the same numbers regardless of your timezone.

Seconds vs milliseconds mixed up

1700000000 is seconds; 1700000000000 is millisecondsTen digits or fewer are read as seconds and 11 digits or more as milliseconds. Use the Unit selector when a value is ambiguous.

Expecting local time from a bare timestamp

1735689600 is 2025-01-01T00:00:00ZUnix time is UTC by definition. Compare the UTC and Local time rows to see the offset applied by your timezone.

Assuming leap seconds are counted

Unix time ignores themUnix time counts SI seconds since the epoch without leap seconds, so it can differ from astronomical time by a few seconds.

Overflowing 32-bit systems

2147483647 is 2038-01-19T03:14:07ZSigned 32-bit second counters overflow in January 2038 (the Y2038 problem). Store 64-bit values or milliseconds.