HIFreeTools

Free Unix Timestamp Converter

Convert a Unix timestamp to a readable date — in both UTC and your local time — or turn a date into a timestamp. Handles seconds and milliseconds.

Quick answer

A Unix timestamp is the number of seconds that have elapsed since 00:00:00 UTC on 1 January 1970 (the “epoch”), not counting leap seconds. For example, 1700000000 corresponds to 14 November 2023, 22:13:20 UTC. Some systems use milliseconds instead of seconds.

Formula & method

The tool reads a timestamp and renders the matching date in UTC and in your browser's local time zone. It auto-detects milliseconds (13-digit values) versus seconds (10-digit values). Converting the other way takes a date and returns the epoch seconds. All of it runs locally in your browser.

Examples

Example 1: The epoch
Input
0
Result
1970-01-01 00:00:00 UTC
Why
Timestamp 0 is the start of Unix time.
Example 2: A recent timestamp
Input
1700000000
Result
2023-11-14 22:13:20 UTC
Why
Seconds since the epoch.
Example 3: Milliseconds
Input
1700000000000
Result
Same date (auto-detected as ms)
Why
13 digits are treated as milliseconds, so it's divided by 1000.

When to use this tool

  • Reading a timestamp from a log, database, API, or JWT.
  • Converting a date to epoch seconds for code or a query.
  • Checking what local time a server timestamp represents.

Common mistakes

  • Mixing seconds and milliseconds — a millisecond value used as seconds lands thousands of years in the future.
  • Forgetting time zones; the same instant shows different local clock times.
  • Assuming Unix time counts leap seconds. It doesn't.

Frequently asked questions

＋ What is a Unix timestamp?

It's the number of seconds since 1 January 1970 at 00:00 UTC. It's a compact, time-zone-free way to represent an instant in time.

＋ Seconds or milliseconds — which is mine?

A 10-digit number is usually seconds; a 13-digit number is milliseconds. The tool auto-detects this for you.

＋ Why does the local time differ from UTC?

UTC is the universal reference. Your local time is UTC shifted by your time zone, so the same timestamp shows two different clock readings.

＋ How do I convert a date back to a timestamp?

Enter the date and the tool returns the epoch seconds for that moment.

＋ Is anything uploaded?

No. All conversions happen in your browser.

  • ✓ Free to use
  • ✓ No sign-up required
  • ✓ Runs entirely in your browser — nothing is uploaded.
  • ✓ Formula and method shown above
Last updated: How we calculateReport a correctionDisclaimer

Provided “as is” for general information only — results may be inaccurate, so verify before you rely on them. No warranty; use at your own risk.

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