How do I know if a timestamp is in seconds or milliseconds?

Unix time in seconds is 10 digits today (e.g. 1700000000, around November 2023) and won't reach 11 digits until the year 2286. Unix time in milliseconds is 1000x larger, so it's 13 digits today. This tool auto-detects the unit by counting digits — 13 or more digits is treated as milliseconds, fewer is treated as seconds.

What does a negative Unix timestamp mean?

The Unix epoch starts at 1970-01-01T00:00:00 UTC. A negative timestamp represents a moment before that date — for example, -86400 is 1969-12-31T00:00:00 UTC. Negative timestamps are valid and this tool converts them correctly.

Which timezone is the converted date shown in?

Both. The UTC row shows the date in Coordinated Universal Time, which is timezone-independent and what's usually stored in logs and databases. The local row shows the same instant converted to your browser's detected timezone, so you can see what time it was where you are.

What is the year 2038 problem?

Many older systems store Unix time as a signed 32-bit integer, which overflows at 2147483647 seconds — 2038-01-19T03:14:07 UTC. After that instant, those systems wrap around to a negative number and misinterpret the date as being back in 1901. Modern 64-bit systems, and this tool, aren't affected — JavaScript's Date uses a 64-bit-safe internal representation well beyond that range.

Is my data uploaded anywhere?

No. All conversion happens locally in your browser using JavaScript's Date and Intl APIs — nothing you type or pick is sent to a server.

UNIX TIMESTAMP CONVERTER

Convert Unix / epoch timestamps to human-readable dates in UTC and your local timezone, and back again. Nothing leaves your browser.

Current timestamp1787565103

Timestamp to date

Unix timestamp (seconds or milliseconds)

Detected as seconds.

UTC

Tue, 14 Nov 2023 22:13:20 GMT

Your local time

Tuesday, November 14, 2023 at 10:13:20 PM UTC

Date to timestamp

Date & time (your local timezone)

Seconds

1787565103

Milliseconds

1787565103000

How to use the timestamp converter

1
To convert a timestamp: paste a Unix timestamp in seconds or milliseconds into the Timestamp field — the unit is auto-detected from the number of digits.
2
Read the resulting date in both UTC and your browser's local timezone, or copy either value.
3
To convert a date: pick a date and time with the date picker and read off the Unix timestamp in seconds and milliseconds.

Questions

How do I know if a timestamp is in seconds or milliseconds?: Unix time in seconds is 10 digits today (e.g. 1700000000, around November 2023) and won't reach 11 digits until the year 2286. Unix time in milliseconds is 1000x larger, so it's 13 digits today. This tool auto-detects the unit by counting digits — 13 or more digits is treated as milliseconds, fewer is treated as seconds.
What does a negative Unix timestamp mean?: The Unix epoch starts at 1970-01-01T00:00:00 UTC. A negative timestamp represents a moment before that date — for example, -86400 is 1969-12-31T00:00:00 UTC. Negative timestamps are valid and this tool converts them correctly.
Which timezone is the converted date shown in?: Both. The UTC row shows the date in Coordinated Universal Time, which is timezone-independent and what's usually stored in logs and databases. The local row shows the same instant converted to your browser's detected timezone, so you can see what time it was where you are.
What is the year 2038 problem?: Many older systems store Unix time as a signed 32-bit integer, which overflows at 2147483647 seconds — 2038-01-19T03:14:07 UTC. After that instant, those systems wrap around to a negative number and misinterpret the date as being back in 1901. Modern 64-bit systems, and this tool, aren't affected — JavaScript's Date uses a 64-bit-safe internal representation well beyond that range.
Is my data uploaded anywhere?: No. All conversion happens locally in your browser using JavaScript's Date and Intl APIs — nothing you type or pick is sent to a server.