Translate between Unix timestamps, ISO 8601 strings and readable dates, in seconds or milliseconds, shown in UTC and your own time zone side by side.
Waiting for a timestamp
Seconds or milliseconds, positive or negative. The unit is detected unless you pick one.
Ten digits is seconds; thirteen is milliseconds. Separators and underscores are ignored.
Nothing to convert yet
Every form of the same instant, side by side — so the one you need is never a calculation away.
Timestamp Converter runs entirely on your device.
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A Unix timestamp counts the seconds since midnight UTC on 1 January 1970. It is how databases, logs and APIs record time, because a single integer has no time zone, no locale and no ambiguity — and it is completely unreadable to a person.
Converting one is only half the problem. The other half is the unit: a timestamp in seconds and the same instant in milliseconds differ by three orders of magnitude and look almost identical at a glance. This converter detects the unit from the magnitude, tells you which it chose, and lets you override it when the guess is wrong.
Going the other way, a date with no time zone is genuinely ambiguous. Midnight in Berlin is not midnight in Chicago, and a tool that silently assumes one of them produces answers that are quietly a day out. So the assumption is a visible control rather than a hidden default, and any date carrying its own Z or offset is read exactly as written.
Every result is shown in both UTC and your own zone, never merged into a single 'time' — which of the two you need is not something the tool can know. Alongside them sit the ISO 8601 form, both epoch units, and how long ago or how far ahead the instant is.
A present-day timestamp in seconds has ten digits; in milliseconds it has thirteen. The converter assumes milliseconds at eleven digits or more and states which it used, so a wrong guess is visible rather than silent.
They are the same instant described from two places. UTC is the zero-offset reference every timestamp is measured against; your local time is that instant shifted by your zone's offset, including daylight saving. Both are shown so neither has to be worked out.
It is read using the assumption you choose — UTC or local. This matters: the same text can name two instants up to a day apart. Adding Z or an offset to the value removes the ambiguity entirely.
Yes. Timestamps before the epoch are negative, and negative values are accepted and converted normally.
Systems that store Unix time in a signed 32-bit integer overflow on 19 January 2038. JavaScript uses a 64-bit floating point number for dates, so this tool is unaffected, but the underlying system that produced a timestamp may not be.
ISO 8601 is read exactly and works everywhere — 2026-03-14T09:15:00Z, with or without an offset. The space-separated form logs and databases print is accepted too. Anything else falls back to your browser's own parsing, which varies between browsers, and the tool says when that has happened.
