Convert Unix timestamps to readable dates and vice versa. Auto-detects seconds vs milliseconds. Runs entirely in your browser.
A Unix timestamp (often called POSIX time or Epoch time) is a system for describing a point in time. It is defined as the number of seconds that have elapsed since the Unix Epoch, which is exactly 00:00:00 on January 1, 1970 UTC (Coordinated Universal Time), minus leap seconds. It is a universal standard heavily used in programming, databases, and APIs because representing time as a single integer makes calculations (like finding the difference between two dates) incredibly simple and avoids the complexities of time zones and daylight saving time.
Standard Unix time is strictly measured in seconds. For example, a timestamp of 1700000000 represents seconds. However, modern programming environments (like JavaScript and Java) require higher precision and use milliseconds since the Epoch. A millisecond timestamp has three extra digits (e.g., 1700000000000 represents the exact same moment but in milliseconds). This converter automatically detects which format you've pasted by checking the length of the string: numbers larger than 10 billion are treated as milliseconds.
The Year 2038 problem is an impending time-formatting bug similar to Y2K. Many older computer systems store the Unix timestamp as a signed 32-bit integer. The highest number a signed 32-bit integer can hold is 2,147,483,647. On January 19, 2038, the Unix timestamp will exceed this number, causing systems representing time as a 32-bit integer to 'roll over' to a negative number. This will cause affected computers to interpret the time as December 13, 1901. Modern operating systems and 64-bit architectures have already solved this by upgrading to 64-bit integers, pushing the capacity limits billions of years into the future.
In JavaScript: Date.now() returns the current time in milliseconds, while Math.floor(Date.now() / 1000) yields seconds. In Python: import time; timestamp = int(time.time()) yields seconds. In PHP: the time() function natively returns the current time in seconds, while microtime(true) returns a float with microseconds.
A Unix timestamp (or Epoch time) represents the exact number of seconds that have elapsed since midnight Coordinated Universal Time (UTC) on January 1, 1970, disregarding leap seconds. Because it translates a complex string like 'Jan 15, 2025' into a single integer, it is universally used across databases, APIs, and operating systems to standardize time calculations across different timezones.
Standard Unix time increments every second (e.g., 1735689600). However, JavaScript and Java natively measure time in milliseconds, meaning their timestamps include three trailing zeros (e.g., 1735689600000). This converter automatically analyzes the length of your input to detect whether it is in seconds or milliseconds, preventing the common "1970 date error" caused by passing seconds to a millisecond-expecting function.
When translating timestamps, ISO 8601 (YYYY-MM-DDTHH:mm:ss.sssZ) is the preferred string format for JSON payloads and APIs. UTC displays the exact universal server time, while Local Time immediately translates the epoch integer into your specific browser timezone layout.