Timestamp

Paste Unix time or an ISO date. Seconds, milliseconds and a readable clock show up here.

Instant

Read a number as

Auto

Seconds

Milliseconds

Paste a number or a date. Now fills the current millisecond.

Learn more about Unix time and ISO 8601

What is this tool?

Unix time counts seconds from 1970-01-01T00:00:00Z. It does not count leap seconds: a POSIX day is 86,400 seconds. Milliseconds are that count times 1,000, which is what JavaScript’s Date uses.

ISO 8601 writes a calendar date, and a time of day with an offset. This page accepts a date-only form or a time with Z or a numeric offset. The ISO line it prints is always UTC, from Date.prototype.toISOString.

Typical use cases

Reading a 10-digit or 13-digit field in a log or a payload.
Turning an ISO timestamp into seconds for an API that asks for them.
Checking the current instant with Now.

How to use it

Paste a number or an ISO date.
Auto treats a number with 13 digits or more as milliseconds, and a shorter number as seconds. Seconds and Milliseconds force that reading.
Copy the line you need. The local line uses your browser’s time zone.

The value stays in your browser. The tool does not upload it. The site keeps your theme, favorites and cookie choice on this device, and it may load a visit counter or ads if you accept them.

Before / after examples

The epoch

Before

After

1970-01-01T00:00:00.000Z

Ten digits and thirteen digits

Before

1700000000
1700000000000

After

2023-11-14T22:13:20.000Z
2023-11-14T22:13:20.000Z

Common mistakes

Twelve digits in Auto

Invalid

170000000000    read as seconds

Valid

170000000000    with Milliseconds

A date-only value such as 2026-10-16 is midnight UTC, which is the ECMA-262 rule for a date without a time. A time without Z or an offset is read in the local time zone. 10/16/2026 is rejected: only the ISO shape is accepted.

Years before 1 and after 9999 are rejected. An unreadable value keeps the previous result on screen.

Good to know

The clock here has millisecond precision, because that is what Date stores. A fraction of a second in the input is kept when it lands on a whole millisecond.

The share link stores the text and the unit switch. The four lines are computed again when the link is opened. Now is not stored by itself: it writes the current millisecond into the field, and that text is what the link keeps.

Did you know?

The Unix epoch is 1970-01-01T00:00:00Z. POSIX defines time_t as seconds since that instant, not counting leap seconds, so every day has 86,400 seconds.

A signed 32-bit time_t overflows at 2038-01-19T03:14:07Z. Values past that instant need a wider integer. This page uses JavaScript numbers, which cover the years 1 through 9999.

ISO 8601 was first published in 1988. The date-time strings this page accepts are the ECMA-262 date time string format: a calendar date, an optional time, and Z or an offset such as +02:00.

Frequently asked questions

Does the date leave my browser?: The tool does not upload what you type. The site keeps your theme, favorites and cookie choice on this device, and it may load a visit counter or ads if you accept them. Parsing runs on your machine. A share link puts the text in the URL fragment: that fragment is not sent with the HTTP request, but anyone who has the link can read it.
Seconds or milliseconds?: Ten digits, such as 1700000000, are seconds. Thirteen digits, such as 1700000000000, are milliseconds. Auto uses the number of digits. If a 12-digit value is milliseconds, switch to Milliseconds.
Why does the local line differ from the ISO line?: The ISO line is UTC. The local line is the same instant in the time zone of the browser, with that zone’s short name.