Epoch converter

What Unix time is

Unix time (also called epoch time or POSIX time) counts the seconds that have passed since 1 January 1970, 00:00:00 UTC. So 1700000000 means 14 November 2023, 22:13:20 UTC. It does not count leap seconds: every day has exactly 86,400 seconds.

A timestamp carries no time zone. It names the same moment in Berlin, Tokyo and New York; only the display converts it to local time. That makes it a robust format for logs, databases, tokens and APIs. Values before 1970 are negative: -1 is 31 December 1969, 23:59:59 UTC.

Seconds, milliseconds, microseconds and nanoseconds

The same time is stored at different resolutions, and you can tell them apart by the number of digits. For present-day moments:

• 10 digits: seconds, e.g. date +%s, PHP time(), JWT fields such as exp and iat.
• 13 digits: milliseconds, e.g. JavaScript Date.now() and Java System.currentTimeMillis().
• 16 digits: microseconds, e.g. in some databases and Go UnixMicro().
• 19 digits: nanoseconds, e.g. Go UnixNano() or Python time.time_ns().

This tool infers the unit from the size of the number: below 10¹¹ it assumes seconds, up to 10¹⁴ milliseconds, up to 10¹⁷ microseconds, and above that nanoseconds. For small values that is not guaranteed to be right: 86400000 could be one day in milliseconds or the year 1972 in seconds. In that case pick the unit by hand. A result far in the future or just after 1970 usually means the wrong unit.

The year-2038 problem and time zones

A signed 32-bit integer tops out at 2147483647, which is 19 January 2038, 03:14:07 UTC. One second later it overflows and wraps to December 1901. Affected are old embedded devices, 32-bit programs using time_t and file formats with 32-bit time fields. MySQL TIMESTAMP columns also end on that date; DATETIME does not have the problem. Unsigned, 32 bits last until 2106.

For time zones the rule is: the timestamp itself is always UTC, only input and display depend on a zone. A wall-clock time without a zone is therefore ambiguous, and when clocks go back one hour happens twice, while when they go forward one hour does not exist. The tool reports both. Store and transmit times in UTC (or with an offset such as +01:00) and convert only for display.

Commands for admins and common questions

Below the converter you will find ready-made commands to copy, for the current value and for “now”:

• Linux: date +%s for now, date -u -d @1700000000 to convert. macOS/BSD: date -u -r 1700000000.
• PowerShell: [DateTimeOffset]::FromUnixTimeSeconds(1700000000). Python: datetime.fromtimestamp(ts, timezone.utc). JavaScript: new Date(ts * 1000).
• MySQL: FROM_UNIXTIME(ts) (in the session time zone). PostgreSQL: to_timestamp(ts).

Why does my log show a different time? Usually it is the same moment in another zone; compare the “ISO 8601 (UTC)” row with the local time. Does Unix time count leap seconds? No, they are skipped, which is why every day has 86,400 seconds. What is the ISO week? The week starts on Monday and week 1 is the one with the year's first Thursday. That is why 1 January 2027 still belongs to week 2026-W53. Is it safe to paste values here? Yes, nothing is sent or stored.

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