Unix timestamp converter
Timestamp to date and date to timestamp. If the number is in milliseconds we spot it, which is the mistake that wastes the most time.
Your figures
Result
- Readable format (UTC)
- Tue, 14 Nov 2023 22:13:20 GMT
- Timestamp in seconds
- 1700000000
- Timestamp in milliseconds
- 1700000000000
- Year
- 2,023
- Day of year
- 318
- Day of week (0 = Sunday)
- 2
What we assume
- Converted in your browser.
- Everything is calculated and printed in UTC, never in your time zone. That is what makes the result the same for everyone.
- A Unix timestamp counts seconds since 1 January 1970 at midnight UTC. Negative values are earlier dates and work too.
- Leap seconds are not counted, exactly as Unix time itself does not: a day is always precisely 86,400 seconds.
- In automatic mode, anything above 10¹¹ is taken as milliseconds, because in seconds that would be the year 5138.
How it is calculated
Unix time counts the seconds elapsed since midnight on 1 January 1970 UTC. It is a plain integer, with no time zone and no formatting: that is why it is used to store and transmit instants, and why it has to be converted to be read.
Seconds or milliseconds
This is the most frequent mistake and the one that wastes the most time. JavaScript works in milliseconds and almost everything else in seconds. Sending milliseconds where seconds were expected lands the date in the year 55,000; the other way round returns January 1970. Since the orders of magnitude are unmistakable, it is detected here and we tell you when we had to infer it.
The year 2038 problem
Stored in a signed 32-bit integer, the counter overflows on 19 January 2038 and jumps back to 1901. Many systems already use 64 bits, but plenty of code does not. If the date you are looking at is past that limit, we say so.
An example
1700000000 is 14 November 2023 at 22:13:20 UTC. The same
number read as milliseconds lands in January 1970 — which is why it pays to check the unit
before the date.
Frequently asked questions
Why is everything in UTC and not my local time?
Because a timestamp has no time zone: it is an absolute instant. Showing it in your local time would make the same timestamp give different answers depending on who is looking, which is exactly what you want to avoid while debugging.
What happens in 2038?
A signed 32-bit counter overflows on 19 January 2038 and wraps to 1901. Modern systems use 64 bits and are unaffected, but older code is not. If your date is past that, we warn you.
Does it count leap seconds?
No, and that is correct: Unix time does not count them either. A day is always 86,400 seconds, even when astronomically one has 86,401.
Does it take dates before 1970?
Yes, with negative timestamps. -86400 is 31 December 1969.
Keep calculating
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Updated on 2026-09-02. Calculations run in your browser; nothing you type is sent to a server.