Is my timestamp in seconds or milliseconds?

Ten digits is seconds; thirteen is milliseconds. JavaScript's Date.now() gives milliseconds, while most databases and Unix tools give seconds, which is where the confusion usually starts.

Why does the date differ from what my database shows?

Almost always a timezone. A timestamp is UTC by definition, and a database client frequently displays it converted to the server's or your session's zone. The number has not changed; the presentation has.

Can a timestamp be negative?

Yes, for dates before 1970. Some systems handle negative timestamps badly, which is worth checking if you store historical dates rather than event times.

What is the year 2038 problem?

A 32-bit signed timestamp overflows on 19 January 2038 and wraps to 1901. Modern systems use 64-bit values, but old columns, embedded devices and long-dated calculations can still hit it.

Unix Timestamp Converter

Converts between Unix timestamps and readable dates in both directions, in UTC and in your own timezone, with seconds and milliseconds handled distinctly.

Runs in your browser — nothing is uploaded

Unix timestamp

Timestamp

Seconds or milliseconds — detected automatically from the number of digits.

Date

9/16/2026, 4:17:04 AM

Interpreted as seconds

ISO 8601: 2026-09-16T04:17:04.000Z
UTC: Wed, 16 Sep 2026 04:17:04 GMT

Need this as an API?

Why use it

Built to be genuinely useful

Seconds and milliseconds are not confused

A ten-digit value is seconds and a thirteen-digit one is milliseconds. Reading one as the other puts you in 1970 or in the year 55000, and both are easy to do by accident.

Both timezones at once

UTC and your local time side by side, because a timestamp discussed across a team is almost always being read in two different zones.

Nothing is uploaded

It runs in your browser. Tokens, keys and customer data routinely end up in these tools, and none of it should have to cross a network to be decoded.

Free, no sign-up

No account, no daily cap, and no feature held back behind a paywall.

How it works

Three steps

1
Paste a timestamp, or pick a date.
2
Read the conversion in UTC and locally.
3
Copy whichever form you need.

What a Unix timestamp is, and what it is not

It is the number of seconds since midnight UTC on 1 January 1970. That makes it a single number with no timezone, no daylight saving and no locale — which is exactly why it is the right thing to store and the wrong thing to show a person.

It is not, strictly, the number of seconds that have elapsed. Leap seconds are ignored by the definition, so a Unix timestamp is the number of seconds assuming every day has exactly 86,400 of them. This matters almost nowhere, and matters enormously in the few places it does.

The year 2038, and why it is still worth knowing about

A signed 32-bit integer runs out on 19 January 2038, at which point the value wraps to a negative number and the date becomes 1901. Most modern systems use 64 bits and are unaffected for longer than the sun will last.

The exposure now is in the corners: embedded devices, an old database column typed INT rather than BIGINT, a file format fixed decades ago. Anything calculating a date more than a decade ahead — a mortgage term, a certificate expiry — reaches 2038 today rather than in 2038.

FAQ

Questions people ask

API access

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