Is my timestamp in seconds or milliseconds?

Count the digits: 10 digits is seconds (good until the year 2286), 13 digits is milliseconds. Pasting seconds where milliseconds are expected lands you centuries in the future — the wrong scale is usually obvious as soon as you convert.

Why does the converted time shift by hours?

Timezone interpretation. A bare timestamp has no timezone — it is an absolute count of seconds from the epoch — so the rendered UTC / ISO values are always the same instant; the hours only "shift" when you compare against a zone-labelled string.

What happens at the 2038 problem?

32-bit systems store seconds in a signed 32-bit integer, which overflows on 2038-01-19. Modern languages and this tool use 64-bit math, so 1681333824 and far-future timestamps convert correctly; the limit only bites old 32-bit runtimes.

Unix Timestamp Converter — Guide

Convert a Unix epoch timestamp (seconds or milliseconds) to a readable date, or turn a date into a timestamp online.

What it is and when to use it

A Unix timestamp — also called epoch or POSIX time — is the number of seconds (or milliseconds) since 1970-01-01T00:00:00Z, UTC, ignoring leap seconds. Seconds are the common form (10 digits, for example 1681333824 = 2023-04-12 21:10:24 UTC), while JavaScript Date.now() and many APIs use milliseconds (13 digits). The same instant has both forms: 1681333824 seconds and 1681333824000 milliseconds are the exact same moment. This tool takes either, shows it alongside ISO 8601 / RFC 3339 / UTC / locale renderings, and can turn a date back into a timestamp — useful for reading log lines, checking whether a JWT exp or cache TTL has already passed, and generating fixtures.

Converts a Unix epoch timestamp (seconds or milliseconds) into a readable date, or turns a date back into a timestamp.

How to use it

Paste a timestamp or enter a date and let the format auto-detect
Read the Unix timestamp in seconds and the milliseconds value
Switch the format if you need ISO 8601, RFC 3339, UTC or your locale

A worked example

Paste a sample timestamp

1681333824

Copy this into the tool, or open Unix Timestamp Converter

Things that trip people up

Unix timestamps in seconds are 10 digits (good until 2286); milliseconds are 13 digits

Questions people ask

Is my timestamp in seconds or milliseconds?: Count the digits: 10 digits is seconds (good until the year 2286), 13 digits is milliseconds. Pasting seconds where milliseconds are expected lands you centuries in the future — the wrong scale is usually obvious as soon as you convert.
Why does the converted time shift by hours?: Timezone interpretation. A bare timestamp has no timezone — it is an absolute count of seconds from the epoch — so the rendered UTC / ISO values are always the same instant; the hours only "shift" when you compare against a zone-labelled string.
What happens at the 2038 problem?: 32-bit systems store seconds in a signed 32-bit integer, which overflows on 2038-01-19. Modern languages and this tool use 64-bit math, so 1681333824 and far-future timestamps convert correctly; the limit only bites old 32-bit runtimes.

Next steps

Open the Unix Timestamp Converter tool

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