Unix Timestamp Converter Online
Convert Unix epochs to readable date-time values or parse dates into epoch seconds and milliseconds.
Computers do not track date strings like "October 12th, 2026, at 3:15 PM" because timezone names, daylight saving offsets, and calendar adjustments (like leap years) make string calculations slow and error-prone. Instead, operating systems and databases represent moments in physical time using a single integer: the number of seconds that have elapsed since the Unix epoch. This epoch is defined as January 1st, 1970, at 00:00:00 Coordinated Universal Time (UTC). This integer makes date comparisons, sorting, and arithmetic simple and fast.
The Difference Between Seconds and Milliseconds
In Unix time, there are two common resolutions: seconds and milliseconds. Legacy Unix systems and protocols like NTP or DNS use seconds. This 10-digit number is standard in databases like PostgreSQL or MySQL when using epoch fields. JavaScript, Java, and modern web APIs, however, default to millisecond resolution. A millisecond timestamp has 13 digits. A common developer mistake is parsing a millisecond timestamp as seconds, which results in dates far in the future, or parsing seconds as milliseconds, which results in dates close to the 1970 epoch. A smart converter detects the digit length to handle this automatically.
Leap Seconds and Time Dilations
Unix time is not a strict count of elapsed physical seconds because of leap seconds. The Earth\'s rotation is gradually slowing down, which means physical days are slightly longer than 86,400 atomic seconds. To keep atomic clocks aligned with solar time, the International Earth Rotation and Reference Systems Service inserts leap seconds periodically. Unix time completely ignores these leap seconds, repeating the second of the leap step. Consequently, calculating durations between dates in Unix time can sometimes introduce errors of a few seconds.
Timezone Conversions and Local Storage
A key rule of database engineering is: always store timestamps in UTC. Storing dates in local time zones like EST or BST creates issues when databases are migrated across regions or when daylight saving transitions occur. Epoch timestamps are inherently timezone-independent because they represent elapsed time relative to UTC. When displaying dates to users, systems read the timezone settings of the user\'s device and offset the epoch accordingly. This client-side approach ensures dates are displayed correctly across different regions.
frequently asked questions
Unix time (or Epoch time) is a system for describing a point in time defined as the total number of seconds that have elapsed since 00:00:00 Coordinated Universal Time (UTC), Thursday, 1 January 1970, excluding leap seconds.
A Unix timestamp in seconds has 10 digits (e.g. 1718236800 corresponds to June 2024). A millisecond timestamp has 13 digits (e.g., 1718236800000). Our converter automatically detects the scale based on the length of the number.
Yes. The converter parses the epoch and displays it in three representations: UTC, ISO 8601, and your computer's active local timezone. This is done client-side so your system timezone settings are handled natively by your browser.
Unix time is not a linear representation of elapsed atomic time because it ignores leap seconds. When a leap second is added, the Unix clock repeats the second or slurs it, meaning some Unix timestamps do not map to unique physical seconds.
The "Year 2038 problem" (Y2K38) affects systems that store Unix timestamps as signed 32-bit integers. On 19 January 2038, the value will overflow the maximum limit of 2,147,483,647, wrapping to negative numbers. Modern 64-bit systems are unaffected.