Unix Timestamp Converter

Convert Unix epoch timestamps to human-readable dates and convert calendar dates back to Unix timestamps. Supports seconds (10 digits) and milliseconds (13 digits), full UTC / local timezone resolution, and live ticking clock.

Current Unix Epoch Time (Seconds)
--------- seconds since Jan 01 1970 (UTC)

Timestamp → Human Date

Human Date → Timestamp

What is a Unix Timestamp (POSIX Time)?

A Unix Timestamp (also known as POSIX time or Epoch time) represents the quantity of seconds that have elapsed since the Unix epoch: January 1, 1970 at 00:00:00 UTC, excluding leap seconds.

Because Unix time is represented as a single numeric value, it eliminates geographic timezone ambiguities and daylight saving time (DST) calculations. It is used as the standard timestamp format across database indexes, distributed logs, Unix file systems, OAuth tokens, and REST APIs.

Seconds (10 Digits) vs. Milliseconds (13 Digits)

A common source of bugs in software development occurs when mixing seconds and milliseconds:

  • Seconds (10 digits): Standard in Linux, C, PHP (time()), Python (time.time()), and MySQL (UNIX_TIMESTAMP()). A value like 1771948800 indicates seconds.
  • Milliseconds (13 digits): Standard in JavaScript (Date.now()), Java (System.currentTimeMillis()), and MongoDB. A value like 1771948800000 indicates milliseconds.

If a 13-digit millisecond value is interpreted as seconds, your code will calculate dates in the far future (approx. year 58,000 AD). Our tool detects this automatically and normalizes the value.

Handling UTC vs. Local Timezones

A Unix timestamp is always UTC. However, when formatting for human eyes, developers frequently need to review both the UTC standard and the end-user’s local time. Our converter presents:

  • UTC Date: The canonical international representation.
  • Local Time: Computed using your system's detected timezone (e.g. EST, PST, GMT, BST, IST).
  • ISO 8601: Standard format (YYYY-MM-DDTHH:mm:ss.sssZ) for JSON APIs.
  • Relative Time: Clear indicators such as "3 hours ago" or "in 2 months".

Frequently Asked Questions

The Unix Epoch is the reference point in time defined as 00:00:00 Coordinated Universal Time (UTC) on Thursday, January 1, 1970. A Unix timestamp measures the continuous number of elapsed seconds (or milliseconds) since this exact moment, ignoring leap seconds.

Look at the digit length: timestamps in seconds currently contain 10 digits (e.g. 1770000000 for the mid-2020s), while timestamps in milliseconds contain 13 digits (e.g. 1770000000000). Our tool automatically detects 13-digit inputs and switches to millisecond precision.

Systems using a signed 32-bit integer to store Unix seconds will overflow on January 19, 2038 at 03:14:07 UTC (timestamp 2,147,483,647). Upon overflow, the integer wraps to a negative number, resetting the clock to December 13, 1901. Modern 64-bit systems represent timestamps safely for approximately 292 billion years.

Local time is subject to daylight saving time (DST) shifts, political timezone adjustments, and ambiguity (such as repeated hours during autumn "fall back"). UTC is monotonically increasing and invariant across all global geographic coordinates, making it the international standard for backend storage and API payloads.