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Unix timestamp converter

Convert exact Unix seconds or milliseconds to UTC and back with a live instant preview.

One exact instant1970-01-01T00:00:00.000Z
Unix seconds0
Unix milliseconds0

UTC · millisecond precision

Processed on your device

How it works & useful details

How it works & limits

Unix time counts from 1970-01-01 00:00:00 UTC. Seconds support up to three fractional digits; milliseconds must be integers. Choose the unit explicitly, including for negative timestamps.

UTC input must use YYYY-MM-DDTHH:mm:ss[.SSS]Z. Years 0001–9999 are supported. Leap seconds and sub-millisecond precision are not represented. No local timezone is inferred.

Your working space

Explore the live preview, then save a copyable text report. Inputs stay on this device and are cleared by refreshing. Dates use the Gregorian calendar, including before its historical introduction.