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Unix Timestamp Converter

Convert between Unix timestamps and readable dates, with the unit detected for you.

Runs in your browser — nothing you type is sent anywhere

The unit is detected from the size of the number — anything with twelve or more digits is milliseconds. Getting this wrong is the usual reason a date comes out in 1970 or in the year 55000.

Or start from a date

The date is read in your own timezone, so the timestamp matches that moment where you are.

About the Unix Timestamp Converter

A Unix timestamp counts seconds since midnight UTC on 1 January 1970. It is how nearly every system stores a moment in time, because a single number has no timezone, no format and no ambiguity — which is exactly why it is unreadable to a person.

The recurring problem is the unit. Unix time is defined in seconds, but JavaScript, Java and many databases work in milliseconds, so the same instant appears as either ten digits or thirteen. Feed one to something expecting the other and the date lands either in January 1970 or tens of thousands of years in the future. This converter detects which you have pasted from the size of the number, since seconds will not reach twelve digits until the year 5138.

The result is shown several ways at once: your local time, UTC, and ISO 8601. Having all three side by side is the fastest way to catch a timezone problem, which is the other half of why timestamps cause bugs — the number itself has no timezone, but the moment you format it, one gets applied.

You can also go the other way, entering a date and time and getting back the timestamp in both units. The date you type is read in your own timezone, so the number describes that moment where you are.

Everything is calculated in the page, so nothing you enter is sent anywhere.

How to use the Unix Timestamp Converter

  1. Paste a timestamp

    Ten digits or thirteen — the unit is worked out from the size of the number, and you can override it if you need to.

  2. Read the date several ways

    Local time, UTC and ISO 8601 are shown together, along with how long ago or how far ahead it is.

  3. Or start from a date

    Use the date and time picker lower down to get the timestamp in both seconds and milliseconds.

  4. Copy the value you need

    Every row has its own copy button, so you can take exactly the format you were after.

Frequently asked questions

How do I know if a timestamp is in seconds or milliseconds?
Count the digits. Ten digits is seconds; thirteen is milliseconds. Seconds since 1970 passed one billion in 2001 and will not reach twelve digits until the year 5138, so anything longer is milliseconds in practice. This tool applies that rule automatically.
What timezone is a Unix timestamp in?
None. It is a count of seconds since a fixed instant in UTC, so it has no timezone at all. A timezone only enters when you format it for display, which is why local time and UTC are shown side by side here.
Why does my timestamp show a date in 1970?
Almost certainly a milliseconds value being read as seconds, which divides the elapsed time by a thousand and lands you a few weeks after the epoch. Switch the unit to milliseconds and it will be correct.
Can it handle dates before 1970?
Yes. Timestamps before the epoch are negative, and negative values convert correctly to their dates in the 1960s and earlier.
What is the year 2038 problem?
Systems storing Unix time in a signed 32-bit integer run out of room in January 2038 and wrap to a negative number, landing in 1901. Modern systems use 64-bit values and are unaffected. This converter uses JavaScript numbers, which handle the full practical range.

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