DEVELOPER TOOLS

Timestamp Converter

Convert Unix timestamps and ISO 8601 date-times locally in this browser. Choose seconds or milliseconds for numeric input; results show both units, UTC, your local timezone, and ISO 8601.

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Current timestamp

Updates every second using this device’s clock.

Unix seconds
Unix milliseconds
ISO 8601
Local time

01 · TIMESTAMP TO DATE

Unix timestamp to date

Use a signed decimal number. Fractional seconds are rounded to the nearest millisecond with JavaScript Math.round; millisecond input must be a whole number.

Enter a Unix timestamp and choose its unit.

02 · DATE TO TIMESTAMP

ISO date-time to Unix timestamp

Include seconds and an explicit timezone, such as Z or +05:30. Date-only and ambiguous local date strings are not accepted.

Enter an ISO 8601 date-time including its timezone.

Timestamp units, rounding, and timezones

Unix time counts milliseconds from 1970-01-01T00:00:00Z. Select Seconds for values such as 1704067200 or Milliseconds for values such as 1704067200000. Negative timestamps represent dates before 1970.

JavaScript dates store whole milliseconds. Fractional Unix seconds are rounded to the nearest millisecond by JavaScript’s Math.round rule; exact half-millisecond ties round toward positive infinity. ISO input accepts one to nine fractional-second digits and rounds them to milliseconds by the same rule. Millisecond input accepts whole numbers only. Dates outside JavaScript’s supported Date range are rejected.

Date input must be a complete ISO 8601 date-time with seconds and an explicit Z or numeric offset, for example 2024-01-01T05:30:00+05:30. Calendar values are checked directly rather than passed to an ambiguous automatic date parser. Local output uses the browser’s timezone (); UTC and ISO output refer to the same instant. All conversion happens in this browser, and input is not sent or saved.