Tutorial · Timestamp Converter · 3 min read

Unix Timestamp to Date: A Practical Guide

Convert a Unix epoch timestamp to a readable date in local time and UTC, and back again. Learn why 10 digits mean seconds and 13 digits mean milliseconds.

Logs, tokens and databases store time as seconds or milliseconds since 1 January 1970 UTC. Reading 1700000000 as a date, or working out why two systems disagree by a factor of a thousand, is a daily task for anyone debugging.

What you'll learn

  • Convert seconds or milliseconds to a date and back
  • Tell 10-digit and 13-digit timestamps apart
  • Read the same instant in local time, UTC and ISO 8601

Step by step

  1. Paste the timestamp

    Open the Unix Timestamp Converter and enter the number. Ten digits are treated as seconds, thirteen as milliseconds, automatically.

  2. Read the conversions

    You get seconds, milliseconds, local time, UTC and an ISO 8601 string. Use Now to grab the current timestamp.

    1700000000
    
    Local:    15/11/2023, 03:43:20  (shown for UTC+05:30; yours will differ)
    UTC:      Tue, 14 Nov 2023 22:13:20 GMT
    ISO 8601: 2023-11-14T22:13:20.000Z
  3. Convert a date back

    Pick a date and time in the second field to get its timestamp in seconds and milliseconds.

Open the tool with this example Runs in your browser. Nothing you paste is uploaded.

Common problems

The date is in the year 55,000

A millisecond value was read as seconds. Check the digit count: 13 digits is milliseconds.

The time is off by a few hours

One system shows local time and the other UTC. Compare the UTC row, or the ISO string ending in Z.

FAQ

What is the year 2038 problem?

Signed 32-bit seconds overflow on 19 January 2038. Modern systems use 64-bit values and are unaffected.