Unix Timestamp Converter
Convert a Unix timestamp to a readable date in your zone and UTC, or turn a date into a timestamp — in seconds or milliseconds.
How it works
A Unix timestamp counts seconds since midnight UTC on 1 January 1970 — the epoch. Because it is always UTC and always a single number, it sidesteps time zones and date formats entirely, which is why systems store time this way.
Seconds and milliseconds are the trap. Unix time is traditionally seconds, but JavaScript's Date works in milliseconds, so a value pasted from one into the other lands you in 1970 or in the year 55000. A ten-digit number is almost certainly seconds; thirteen digits is milliseconds.
The timestamp itself has no time zone. The tool shows both your local rendering and UTC, because the same instant is a different wall-clock time depending on where you are standing.
The formula
Timestamp to date
date = epoch + (timestamp × 1000) ms
Date to timestamp
timestamp = milliseconds since epoch ÷ 1000
Seconds vs milliseconds
10 digits ≈ seconds · 13 digits ≈ milliseconds
Worked examples
| Scenario | Working | Result |
|---|---|---|
| 0 | The epoch itself | 1 Jan 1970 00:00:00 UTC |
| 1700000000 | 10 digits, seconds | 14 Nov 2023 UTC |
| 1700000000000 | 13 digits, milliseconds | The same instant |
When you'd use it
- Reading a timestamp out of a log or database
- Debugging an API that returns epoch time
- Converting a date into a timestamp for a query
- Checking whether a value is in seconds or milliseconds
Common questions
Is my timestamp in seconds or milliseconds?
Count the digits. Current timestamps are 10 digits in seconds and 13 in milliseconds. If a date comes out in 1970 you have fed milliseconds into a seconds field; if it lands thousands of years ahead, the reverse.
Does a Unix timestamp have a time zone?
No — it is always UTC by definition. The time zone only appears when you render it for a person, which is why this tool shows both your local time and UTC for the same number.
What is the 2038 problem?
A signed 32-bit timestamp overflows on 19 January 2038, which will break systems still storing epoch time in 32 bits. Modern systems use 64-bit values and are unaffected for longer than anyone needs to worry about.