Timestamp Converter

What Is a Unix Timestamp?

A Unix timestamp — also called Unix epoch time, POSIX time, or simply epoch — is the number of seconds that have elapsed since January 1, 1970 at 00:00:00 UTC. It is the most widely used method for representing a specific point in time in computer systems, databases, APIs, and log files.

Unlike human-readable date formats (which vary by locale and timezone), a Unix timestamp is a single integer that is unambiguous, timezone-independent, and trivially comparable. 1705312200 means exactly the same moment in time regardless of where you are in the world.

Seconds vs. Milliseconds — Which Precision Does Your Timestamp Use?

Modern systems use two common precisions:

• Seconds — A 10-digit number, e.g. 1705312200. Used by Unix/Linux, Python’s time.time(), most server-side APIs, JWT iat/exp claims, and HTTP headers.
• Milliseconds — A 13-digit number, e.g. 1705312200000. Used by JavaScript’s Date.now(), Java’s System.currentTimeMillis(), MongoDB, and most browser-originated timestamps.

This tool auto-detects the precision: any value ≥ 10,000,000,000 (10 billion) is treated as milliseconds; everything below is treated as seconds. The boundary value of 10 billion seconds corresponds to the year 2286 — a timestamp in seconds will never reach that value in practice, so the detection is unambiguous for all real-world timestamps.

How Timezones Affect Timestamp Conversion

A Unix timestamp itself is always in UTC — there is no “timezone” embedded in the number. Timezone only matters when you display the date in a human-readable format. For example, 1705312200 represents:

• UTC: Mon, 15 Jan 2024 10:30:00 GMT
• UTC+8 (Asia/Shanghai): Mon, 15 Jan 2024 18:30:00
• UTC-5 (America/New_York): Mon, 15 Jan 2024 05:30:00

This tool shows the same timestamp in both UTC and your browser’s local timezone, so you can compare them directly without mental arithmetic.

What Is ISO 8601?

ISO 8601 is the international standard for representing dates and times. The format used by this tool — 2024-01-15T10:30:00.000Z — is the most common computer-friendly form:

• 2024-01-15 — Year, month, day (big-endian, unambiguous)
• T — Separator between date and time
• 10:30:00.000 — Hours, minutes, seconds, milliseconds
• Z — UTC timezone (equivalent to +00:00)

ISO 8601 is used by JSON (JSON.stringify(new Date())), HTML datetime attributes, REST API responses, and most programming language date libraries.

Frequently Asked Questions

Why does my timestamp show a date in 1970? The Unix epoch starts at January 1, 1970. If your timestamp is very small (e.g. 0 or 1000), the result will be in 1970. This is correct — it means the timestamp is 0 or 1000 seconds after the epoch. Check whether you accidentally omitted digits from the timestamp.

How do I get the current Unix timestamp in JavaScript? Use Math.floor(Date.now() / 1000) for seconds or Date.now() for milliseconds. This tool displays the live current timestamp at the top of the page.

How do I get the current Unix timestamp in Python? Use import time; time.time() for a float in seconds, or int(time.time()) for an integer.

Can I convert a date string back to a Unix timestamp? Yes. Switch to the “Date → Timestamp” mode and enter an ISO 8601 date string such as 2024-01-15T10:30:00Z. The tool returns both seconds and milliseconds.

Is my data private? Yes. All processing happens entirely in your browser. No timestamp, date string, or any input is ever sent to a server.