Unix Timestamp Converter

Convert a Unix timestamp to a readable date, or a date back to epoch time. Auto-detects seconds vs. milliseconds and shows UTC, local, ISO 8601, and relative time.

Unix Timestamp Converter features

Two-Way Conversion

Turn a Unix timestamp into a date, or convert a date string back into epoch time, both in one place.

Auto Unit Detection

Detects seconds vs. milliseconds automatically — values with 12 or more digits are treated as milliseconds.

ISO 8601 & UTC Output

See the timestamp as a standards-compliant ISO 8601 string and a full UTC date string at a glance.

Local Time Zone

Shows the same instant in your browser's local time zone so you do not have to do the math.

Relative Time

Displays a human-friendly relative phrase like "in 3 hours" or "2 days ago" next to the exact date.

100% In-Browser

All conversion happens locally in your browser — no timestamps are uploaded, logged, or stored.

Overview

A Unix timestamp (also called epoch time or POSIX time) is a single number that counts the seconds elapsed since 00:00:00 UTC on January 1, 1970, ignoring leap seconds. Because it is timezone-independent, it is the standard way databases, APIs, and log files store a point in time. For example, 1700000000 represents November 14, 2023.

Some systems store timestamps in milliseconds instead of seconds — JavaScript's Date.now() is a common example. This converter auto-detects the unit: a value with 12 or more digits is treated as milliseconds, and shorter values are treated as seconds, so you rarely need to think about which one you pasted.

This tool converts in both directions. Paste a number to get the matching date, or type a date string to get its Unix time. It displays the value as Unix seconds, Unix milliseconds, ISO 8601 (UTC), a full UTC string, your local time in the browser's time zone, and a friendly relative time like "in 3 hours" or "2 days ago".

Everything runs entirely in your browser. Nothing you type is uploaded or stored on a server, which makes it safe for timestamps from internal logs and private systems. Leave the field empty and it shows the current time, updating as a quick reference clock.

How to use the Unix Timestamp Converter

Paste a Unix timestamp (in seconds or milliseconds) into the input field, or leave it empty to see the current time.
Alternatively, type a date string to convert it the other way, into Unix time.
Let the converter auto-detect the unit — values with 12 or more digits are read as milliseconds, shorter ones as seconds.
Read the results: Unix seconds, Unix milliseconds, ISO 8601 (UTC), the full UTC string, your local time, and the relative time.
Check the local time row to see the value in your browser's own time zone.
Copy the format you need straight from the output.

Good to know

A few details worth keeping in mind:

Unit auto-detection is heuristic. A value with 12 or more digits is treated as milliseconds and shorter values as seconds. Unusual inputs may be interpreted in the unit you did not intend, so check the labeled output rows.
UTC vs. local. The ISO 8601 and UTC outputs are fixed to UTC, while the local time reflects your browser's time zone — they describe the same instant, just displayed differently.
Leap seconds are not modeled. Unix time assumes 86,400 seconds per day, matching the standard used by most systems.
Relative time is approximate. Phrases like "in 3 hours" are rounded for readability; rely on the exact ISO 8601 or Unix values for precision.

Private by design

Every byte you paste into the Unix Timestamp Converter is processed locally in your browser. Formatly makes no network request with your data, logs nothing, and stores nothing on any server — so it is safe for API responses, tokens, configuration and other sensitive content. Your most recent input and theme are saved only in your own browser's local storage.

Unix Timestamp Converter FAQ

Is my data private and safe to use here?

Yes. This converter runs 100% in your browser. The timestamps and dates you enter are never uploaded, logged, or sent to any server, so it is safe to use with values pulled from private logs or internal systems.

Does the converter work offline?

Yes. Once the page has loaded, all conversion happens locally with no network calls. You can disconnect from the internet and it will keep working, since nothing is processed on a server.

What is the difference between Unix seconds and milliseconds?

Unix seconds count whole seconds since January 1, 1970 UTC (for example 1700000000), while milliseconds count thousandths of a second (for example 1700000000000). Many languages use milliseconds — JavaScript's Date.now() is one — so the same instant has a longer number. This tool auto-detects which you pasted: 12 or more digits is read as milliseconds.

What happens if I leave the input empty?

If you leave the field empty, the converter shows the current time in every format — Unix seconds, milliseconds, ISO 8601, UTC, local time, and relative time — so it doubles as a quick reference clock.

What time zone are the results shown in?

The ISO 8601 and UTC outputs are always in Coordinated Universal Time (UTC). The local time row uses your browser's own time zone, so the same instant is shown both ways without any manual conversion.

Can I convert a date back into a Unix timestamp?

Yes. Enter a date string and the tool converts it into Unix time, giving you both the seconds and milliseconds values alongside the other formats.

Does the timestamp account for leap seconds?

No. Like the Unix time standard itself, this converter ignores leap seconds. Unix time treats every day as exactly 86,400 seconds, which is the expected behavior for almost all software and matches how databases and APIs store timestamps.