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Unix Timestamp Converter

Convert Unix timestamps to human dates (UTC, local, ISO 8601) and back — instantly, in your browser.

Privacy: your files never leave your device. All processing happens locally in your browser.

How to use

  1. 1.To decode a timestamp, paste the Unix value into the "Timestamp → Date" field and pick Seconds or Milliseconds.
  2. 2.Read the results: ISO 8601 and UTC are timezone-independent; "Local time" reflects your device timezone; "Relative" shows the distance from now.
  3. 3.To go the other way, type or paste a date (e.g. 2023-11-14T22:13:20Z) into the "Date → Timestamp" field to get the epoch value in both seconds and milliseconds.

About Unix Timestamp Converter

A Unix timestamp is the number of seconds elapsed since the Unix epoch — 1970-01-01T00:00:00Z (UTC). It's the timekeeping backbone of almost every system you touch: server logs, API responses, database rows, JWT expiry claims, cron jobs, and Git commits all store time as a plain integer counting up from that 1970 midnight in Greenwich. Because it's just a number with no timezone attached, it's compact, sortable, and unambiguous — but impossible to read at a glance. This converter bridges that gap in both directions, entirely in your browser.

Parse a timestamp and you'll see four views at once: ISO 8601 (2023-11-14T22:13:20.000Z), a readable UTC string, your own local time, and a relative label like "3 hours ago" or "in 2 days." Go the other way and paste any date — an ISO 8601 string, a plain "2023-11-14 22:13:20 UTC," or a natural date — to get back the exact epoch value in both seconds and milliseconds.

One detail trips up developers constantly: seconds versus milliseconds. Unix time is defined in seconds, but JavaScript's Date, Java's System.currentTimeMillis(), and many APIs work in milliseconds — 1000× larger. A 10-digit number is almost always seconds; a 13-digit number is milliseconds. This tool auto-detects by digit count and lets you override the unit, so you never accidentally land in the year 55000 because you fed milliseconds into a seconds field.

There's also the famous Year 2038 problem: systems that store Unix time in a signed 32-bit integer overflow at 03:14:07 UTC on 19 January 2038, wrapping around to 1901. Modern platforms use 64-bit integers and are safe for billions of years, but the bug still lurks in legacy embedded and database code — which is exactly why being able to eyeball what a raw timestamp actually means is a daily debugging necessity.

Every conversion here is computed locally with the platform Date object and explicit UTC formatting, so nothing is uploaded and your data never leaves the page. It's built for exactly the moments you're staring at a log line, an API payload, or a DB column and need to know what time it really is.

Methodology & sources

Unix time = seconds since the Unix epoch 1970-01-01T00:00:00Z; conversions use the platform Date with explicit UTC formatting (ISO 8601).

Frequently asked questions

What is a Unix timestamp?
It's the number of seconds that have elapsed since the Unix epoch, 1970-01-01T00:00:00Z (UTC). It has no timezone of its own, which makes it a compact, unambiguous way to store a moment in time across logs, APIs, and databases.
How do I know if my number is in seconds or milliseconds?
Count the digits. A current timestamp in seconds is about 10 digits; in milliseconds it's about 13 digits (1000× larger). This tool auto-detects based on length, and you can override the unit with the Seconds/Milliseconds selector if needed.
What is the Year 2038 problem?
Systems that store Unix time in a signed 32-bit integer overflow at 03:14:07 UTC on 19 January 2038 and wrap back to 1901. 64-bit systems are unaffected. Modern browsers use 64-bit doubles, so this converter handles dates far beyond 2038 correctly.

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