Unix Timestamp Converter

What Is a Unix Timestamp?

A Unix timestamp (also called an Epoch timestamp or POSIX time) is the number of seconds that have elapsed since 00:00:00 UTC on January 1, 1970 — known as the "Unix Epoch." It is the most widely used time representation in computing, used by databases, APIs, log files, and programming languages to store and compare dates without timezone ambiguity.

For example, the Unix timestamp 1700000000 corresponds to November 14, 2023, at 22:13:20 UTC. Our converter lets you instantly translate between human-readable dates and Unix timestamps in both directions — ideal for debugging APIs, analyzing logs, or working with database timestamps.

Human Date to Unix Timestamp (and Back)

Converting between Unix timestamps and human-readable dates is a fundamental task in software development. Our tool handles both directions:

• Date to Unix timestamp — Enter a calendar date and the tool returns the corresponding Unix timestamp in both seconds and milliseconds.
• Unix timestamp to date — Paste any Unix timestamp (in seconds or milliseconds) and the tool returns the equivalent UTC date and time in a human-readable format.

The converter automatically detects whether your input is in seconds (10-digit numbers) or milliseconds (13-digit numbers), so you don't need to worry about the unit — just paste the number and get the result.

Why Programmers Use Unix Timestamps

• Timezone-neutral — A Unix timestamp represents a single, absolute moment in time in UTC. Converting to local time is done at display time, eliminating ambiguity in storage.
• Simple integer arithmetic — Comparing two timestamps is as easy as subtracting integers. No need to handle timezone offsets, DST changes, or calendar quirks when computing durations.
• Universal language support — Every major programming language (Python, JavaScript, Java, Go, Rust, PHP, Ruby, C) has built-in support for Unix timestamps, making them the lingua franca of date/time in software.
• Sorting and comparison — Timestamps are easily sortable as numbers, making them ideal for database indexes and ordered event streams.
• Database efficiency — Storing a 32-bit (or 64-bit) integer is more space-efficient and faster to index than storing a formatted date string.

Common Uses in Software Development

• API responses — REST APIs commonly return dates as Unix timestamps to avoid timezone-related parsing issues across different client environments.
• JWT expiry (exp claim) — JSON Web Tokens store their expiration time as a Unix timestamp in the exp field. Debugging an expired token often requires converting this number to a readable date.
• Database fields — MySQL, PostgreSQL, MongoDB, and Redis all support Unix timestamp storage. Database logs and audit trails frequently use epoch time.
• Log analysis — Web server logs, application logs, and security event logs often record timestamps in Unix time for consistency across distributed systems.
• Cache-control headers — HTTP headers like Last-Modified and Expires are related to Unix time, and debugging caching issues often involves timestamp conversion.

How to Use the Unix Timestamp Converter

1. Select your conversion direction using the Mode dropdown — either "Date to Unix timestamp" or "Unix timestamp to Date."
2. For Date to Unix: enter a calendar date. The tool will return the Unix timestamp for midnight UTC on that date.
3. For Unix to Date: paste the timestamp (10-digit seconds or 13-digit milliseconds). The tool auto-detects the unit and returns the UTC date and time.
4. Click Calculate and use Copy result to grab the output for use in your code or documentation.

Frequently Asked Questions

• What is the Unix Epoch?
  The Unix Epoch is the reference point for Unix time — it is defined as 00:00:00 Coordinated Universal Time (UTC) on Thursday, January 1, 1970. A Unix timestamp is simply the number of seconds (or milliseconds) that have elapsed since that moment. The Epoch was chosen when Unix was being developed at Bell Labs in the late 1960s and early 1970s, and it has since become the universal starting point for time in computing.
• Does Unix time account for leap seconds?
  No. Unix time does not account for leap seconds. The POSIX standard defines Unix time as if every day has exactly 86,400 seconds, even though leap seconds occasionally add an extra second to keep UTC in sync with Earth's rotation. In practice, this means Unix timestamps can be off by the number of leap seconds that have occurred since 1972 (27 leap seconds as of 2017) compared to TAI (International Atomic Time). For most software applications, this difference is negligible.
• What is the maximum Unix timestamp — the Year 2038 problem?
  The Year 2038 problem (also called Y2K38) affects systems that store Unix timestamps as a signed 32-bit integer. The maximum value of a 32-bit signed integer is 2,147,483,647, which corresponds to 03:14:07 UTC on January 19, 2038. After that point, 32-bit systems will overflow and roll back to a negative number, potentially causing date calculation errors. Modern systems use 64-bit integers for timestamps, which can represent dates up to approximately 292 billion years in the future — eliminating the problem entirely.
• What's the difference between Unix time in seconds vs milliseconds?
  The traditional Unix timestamp is measured in seconds and is typically a 10-digit number (e.g., 1700000000). Many modern systems and programming languages — particularly JavaScript, which uses Date.now() — work in milliseconds, resulting in a 13-digit number (e.g., 1700000000000). To convert from milliseconds to seconds, divide by 1000. Our converter automatically detects which unit you're using based on the length of the number you enter.