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Timestamp converter
Unix ↔ ISO / local / UTC, ms and s auto-detect.
Converting Unix time
Paste a Unix timestamp or an ISO date and get the other forms: seconds, milliseconds, UTC and your local time. Seconds and milliseconds are detected automatically by magnitude, which is the ambiguity that causes most conversion bugs.
Unix time counts seconds since 1970-01-01 UTC and has no timezone of its own — the timezone appears only when you format it.
Why did my timestamp land in 1970 or in the year 55000?
Seconds and milliseconds got mixed up. A value around 1.7 billion is seconds; around 1.7 trillion is milliseconds. Passing milliseconds to a function expecting seconds throws the date far into the future, and the reverse lands you next to the epoch.
Does Unix time account for leap seconds?
No. It pretends every day has exactly 86400 seconds, so during a leap second the same value is used twice. That is deliberate — it keeps the arithmetic simple — but it means Unix time is not a precise count of elapsed seconds since 1970.
Which format should I store in a database?
Store an absolute instant — a timestamptz column or UTC — and format for the user at display time. Storing local time without an offset is the bug that surfaces twice a year at the daylight-saving boundary.
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