How does it tell seconds and milliseconds apart?

It's determined automatically from the number of digits entered (11 digits or fewer is treated as seconds, 12 or more as milliseconds).

What is a Unix timestamp?

It's the number of seconds (or milliseconds) that have elapsed since 00:00:00 UTC on January 1, 1970.

Is the value I enter sent to a server?

No. It's calculated using the JavaScript Date object based on your browser's local time zone.

🗓️ Timestamp Converter

Instantly convert Unix timestamp ↔ date. (Seconds/milliseconds auto-detected)

Current Unix timestamp

Timestamp → Date

The converted date will be shown here

Date → Timestamp

The converted timestamp will be shown here

How to use

Enter a timestamp (in seconds or milliseconds) to have it auto-converted to a date.
Pick a date/time to have it auto-converted to a Unix timestamp.
All calculations are based on your browser's local time zone.

🎯 Use Cases

Check what actual date a timestamp value in a log file corresponds to — instantly turn numbers in server logs or error traces into readable dates
Debug Unix time fields in API responses — quickly verify fields like created_at or expires_at when seconds and milliseconds get mixed up
Calculate a timestamp value for a specific date to store in a DB — pre-compute the timestamp for a specific moment for test data or expiration dates
Check JWT exp/iat claims — instantly see what an expiration (exp) number from a JWT decoder actually corresponds to

Example

Input

1735689600

Output

UTC: Wed, 01 Jan 2025 00:00:00 GMT
ISO: 2025-01-01T00:00:00.000Z

A number of 11 digits or fewer is read as seconds, so the Unix timestamp 1735689600 is converted to a date. The UTC and ISO values above are time-zone independent; the live tool also shows a "Local:" line based on your browser's time zone.

Timestamp units by language/system

Language/System	Default unit	Note
JavaScript `Date.now()`	Milliseconds	Shown as a 13-digit number
Python `time.time()`	Seconds (with decimals)	10-digit integer part + fraction
Unix `date +%s`	Seconds	10-digit integer
MySQL `UNIX_TIMESTAMP()`	Seconds	10-digit integer
JWT `exp`/`iat` claims	Seconds	Per the RFC 7519 standard

"The timestamp is 13 digits, so why does the date look wrong?" — issues like this usually come from confusing seconds and milliseconds. This tool auto-detects by digit count, but knowing which language or system the raw value came from lets you judge more reliably.

FAQ

How does it tell seconds and milliseconds apart?: It's determined automatically from the number of digits entered (11 digits or fewer is treated as seconds, 12 or more as milliseconds).
What is a Unix timestamp?: It's the number of seconds (or milliseconds) that have elapsed since 00:00:00 UTC on January 1, 1970. Dates after January 19, 2038 are subject to the well-known "Year 2038 problem," an overflow that occurs when the value is stored as a signed 32-bit integer.
Can I enter a negative timestamp?: Yes. Dates before January 1, 1970 are represented as negative timestamps, and this tool converts negative input to a date correctly.
Is the value I enter sent to a server?: No. It's calculated using the JavaScript Date object based on your browser's local time zone.