Convert Unix timestamps to human-readable dates and back. Auto-detects seconds, milliseconds and microseconds; shows ISO 8601, UTC, local time and relative time.
How Unix timestamps work
A Unix timestamp counts time from the epoch — 1 January 1970 00:00:00 UTC. Systems disagree on the unit: classic Unix uses seconds, JavaScript uses milliseconds, some databases use micro- or nanoseconds. This tool detects the unit from the number of digits, converts in both directions, and renders the moment as ISO 8601, UTC, your local time and a relative phrase.
Date.now() = milliseconds since 1970-01-01T00:00:00ZFrequently asked questions
How do I tell seconds from milliseconds?
By size: current times are 10 digits in seconds (≈1.7 billion) and 13 digits in milliseconds. The converter uses digit count to auto-detect — ten or fewer digits is treated as seconds, 12–14 as milliseconds. Everything converts locally in your browser.
What is the year-2038 problem?
Systems that store seconds in a signed 32-bit integer overflow on 19 January 2038, wrapping to 1901. Modern 64-bit systems and JavaScript's millisecond doubles are unaffected, but old embedded systems and legacy databases can still be bitten.
Are the conversions timezone-safe?
Yes. A Unix timestamp is always UTC — it has no timezone of its own. The converter shows the same instant three ways: ISO 8601/UTC (timezone-independent) and your local time, which simply renders that instant in your browser's timezone.
Last updated: 7 July 2026
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