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What is a Unix Timestamp?

A Unix timestamp (also known as Epoch time, POSIX time, or Unix Epoch time) is a system for tracking time by counting the number of seconds that have elapsed since 00:00:00 Coordinated Universal Time (UTC) on January 1, 1970, excluding leap seconds. This point in time is referred to as the Unix Epoch.

Unix timestamps are widely used in operating systems, programming languages, databases, and file systems as a standardized way to represent a moment in time. Because timestamps are just integers, they are easy to store, compare, sort, and transmit across different systems and programming languages without timezone ambiguity.

Our free online Unix timestamp converter allows you to convert between human-readable dates and Unix timestamps, supporting multiple output formats including ISO 8601, RFC 2822, ATOM, COOKIE, and more. All processing happens locally in your browser.

Key Features

  • Timestamp to Date: Convert Unix timestamp values to human-readable date and time in various formats
  • Date to Timestamp: Convert formatted dates back to Unix timestamp values with ease
  • Multiple Output Formats: Support for ATOM, COOKIE, ISO 8601, RFC 822, RFC 2822, RFC 3339, and more
  • Batch Conversion: Convert multiple timestamps or dates at once — one per line, up to 100,000 entries
  • Current Timestamp Display: Real-time display of the current Unix timestamp with auto-refresh
  • Multi-Language Code Examples: Built-in code snippets for getting timestamps in 15+ programming languages
  • Client-Side Processing: All conversions are performed locally in your browser — zero data upload

Common Use Cases for Unix Timestamps

  • Database Operations: Store timestamps in databases as integers for efficient indexing and comparison — most databases including MySQL, PostgreSQL, and SQLite support Unix timestamp storage
  • API Development: Timestamps are the standard for representing dates in RESTful APIs, JSON payloads, and JavaScript applications
  • Log Analysis: System and application logs often use Unix timestamps — quickly convert log entries to readable dates for debugging and analysis
  • File Metadata: Operating systems store file creation, modification, and access times as Unix timestamps
  • Cross-Platform Development: When building applications that run across multiple timezones, Unix timestamps eliminate the complexity of timezone conversions
  • Data Migration: When moving data between systems with different date formats, converting all dates to timestamps ensures consistency

How to Use the Unix Timestamp Converter

  1. Timestamp to Date: Enter one or more Unix timestamps (one per line) in the input field — the converted dates will appear instantly in your chosen format
  2. Date to Timestamp: Switch to date input mode and enter dates in the format YYYY-MM-DD HH:mm:ss — the corresponding Unix timestamps will be calculated automatically
  3. Select Output Format: Choose from various date format presets including ISO 8601, RFC 2822, ATOM, COOKIE, and more
  4. Copy Results: Use the copy button to copy converted values to your clipboard

All processing is done locally in your browser. Your data never leaves your device.

Frequently Asked Questions About Unix Timestamps

What happens when the Unix timestamp overflows in 2038?
The Year 2038 problem (also known as the Y2K38 problem or Unix Millennium Bug) arises because many systems store timestamps as a signed 32-bit integer. At 03:14:07 UTC on 19 January 2038, the value will overflow from 2147483647 to -2147483648. However, most modern systems now use 64-bit integers for timestamps, which will not overflow for approximately 292 billion years. If you are maintaining legacy 32-bit systems, they should be upgraded or patched before 2038.
Why January 1, 1970? What is the significance of this date?
January 1, 1970 at midnight UTC was chosen as the Unix Epoch for historical reasons related to the early development of the Unix operating system at Bell Labs. This date was convenient because it marked a clean break point, and time values before 1970 could be represented as negative numbers. The specific date was finalized in the early 1970s as Unix was being standardized, and it has remained the epoch ever since due to widespread adoption.
Are Unix timestamps affected by timezones or daylight saving time?
No, Unix timestamps are timezone-independent. A Unix timestamp represents the same moment in time everywhere in the world. The timestamp value does not change regardless of the observer's location or whether daylight saving time is in effect. Only when converting a timestamp to a human-readable date does timezone and DST come into play. This property is what makes Unix timestamps so useful for international systems and distributed applications.
What is the difference between seconds and milliseconds in Unix timestamps?
Standard Unix timestamps are measured in seconds since the epoch. However, many programming environments (particularly JavaScript and some NoSQL databases) use millisecond precision — the number of milliseconds since the Unix epoch. A millisecond timestamp is exactly 1,000 times larger than its second-based equivalent. Our tool handles both formats: if you enter a 13-digit number (milliseconds), it will be treated as milliseconds, while a 10-digit number is treated as seconds.
Can I convert dates before January 1, 1970?
Yes, dates before January 1, 1970 are represented as negative Unix timestamps. For example, December 31, 1969 at 23:59:59 UTC is timestamp -1. Our converter fully supports negative timestamps for historical dates, and all date-to-timestamp conversions for dates before 1970 will correctly return negative values. The range of supported dates depends on your browser's capabilities, but typical support spans from approximately 100,000,000 BC to 100,000,000 AD.