Developer Tool
The same moment in time can be written as a 10-digit, 13-digit, 16-digit, or 19-digit number depending on whether the timestamp is in seconds, milliseconds, microseconds, or nanoseconds. Paste any one and see all four.
Digit count decides the unit automatically: ~10 digits = seconds, ~13 = milliseconds, ~16 = microseconds, ~19 = nanoseconds (for dates in the 2001–2286 range).
There's no metadata attached to a bare integer — a value like 1750000000 is unambiguous only because it happens to fall in a sane range for "seconds since 1970 right now." Systems that pass timestamps between services (a Python backend in seconds, a JavaScript frontend in milliseconds, a Go service using nanoseconds) will happily accept the wrong unit and produce a date that's off by a factor of 1,000, one million, or one billion — with no error, just a wrong-looking date that's easy to mistake for a timezone bug instead.
Count the digits. 10 digits is seconds until the year 2286. 13 digits is milliseconds. 16 is microseconds. 19 is nanoseconds. If a value doesn't cleanly fit one of these lengths, it likely isn't Unix time at all — check the Historical Epoch Converter for other common formats it might be instead.
Related
Excel, .NET ticks, GPS time, Julian day and other non-Unix formats.
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