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What Is a Unix Timestamp?
A Unix timestamp is the number of seconds since 1970-01-01 00:00:00 UTC, without time zones or leap seconds. It is an absolute instant, but local display changes with the time zone.
Seconds and milliseconds
Seconds are about 10 digits (around 1.7e9 in 2026); milliseconds are about 13.
JavaScript Date uses milliseconds; many backend APIs use seconds.
Year 2038
Signed 32-bit seconds overflow on 2038-01-19; modern systems mostly use 64-bit.
Embedded and legacy systems still need care.
FAQ
Does a timestamp include a time zone?
No; it is a UTC instant, and a zone is applied for display.
Why 1970?
It is the historical Unix epoch, convenient for arithmetic.
Sources
Related calculators
Timestamp ConverterConvert Unix timestamps to local, UTC and ISO dates, or dates to second/millisecond timestamps.More guides
Timestamps and Time ZonesRead guideKEEP READING
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