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Timestamp ↔ date

Turn numeric timestamps into readable dates, and dates into milliseconds.

How to use
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1 second = 1,000 ms · Selected zone applies unless Z/±HH:mm is specified

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QUICK GUIDE

One moment, different representations.

Unix timestamps measure time since January 1, 1970 at 00:00:00 UTC. This tool uses milliseconds. Negative values represent earlier times.

  1. 01

    Choose a direction

    Convert a millisecond number to a date, or a date to milliseconds.

  2. 02

    Enter a time and time zone

    Use YYYY-MM-DD HH:mm:ss.SSS. A trailing Z or an offset such as +09:00 takes precedence over the selected time zone.

  3. 03

    Compare or convert back

    Compare KST, UTC, and milliseconds for the same instant. Use Reverse conversion to check the round trip.

SAME MOMENT

1735689600123 milliseconds

UTC 2025-01-01 00:00:00.123
KST 2025-01-01 09:00:00.123

These are the same instant in different zones. Multiply a seconds-based timestamp by 1,000 before entering it.

Frequently asked questions

Does it detect seconds versus milliseconds?

No automatic guessing: values always mean milliseconds. For example, 1000 is one second after the epoch and 0 is 1970-01-01 00:00:00 UTC.

What happens if I specify a time zone?

A trailing Z or ±HH:mm takes precedence. Otherwise, dates use the selected KST (+09:00) or UTC zone. KST is fixed at +09:00 and does not model historical time-zone changes.

What date range and precision are supported?

Years 0001–9999 in UTC, with millisecond precision. Invalid dates, leap seconds, and sub-millisecond input are rejected.