Unix Timestamp Converter
Convert between Unix timestamps (epoch seconds or milliseconds) and human-readable dates. Supports multiple timezones, an instant "now" fill, and relative time display for developers.
Unix Timestamp Basics
A Unix timestamp represents a date and time as the number of seconds elapsed since 00:00:00 UTC on January 1, 1970 (the Unix epoch). Below is a table of well-known timestamp values and the dates they represent.
| Timestamp (seconds) | UTC date & time | Note |
|---|---|---|
| 0 | 1970-01-01T00:00:00Z | The Unix epoch (the starting point of all timestamps) |
| 1000000000 | 2001-09-09T01:46:40Z | The moment the timestamp reached one billion seconds (the "Unix billennium") |
| 1234567890 | 2009-02-13T23:31:30Z | A value that became a minor curiosity for containing the digits 1 through 9 in sequence |
| 2147483647 | 2038-01-19T03:14:07Z | The Year 2038 problem: the maximum value of a signed 32-bit integer (it overflows one second later) |
Usage Tips
- A 10-digit value is usually in seconds, while a 13-digit value is usually in milliseconds. Selecting "Auto-detect" infers the unit from the digit count for you.
- Paste a timestamp straight from a server log or API response to check its equivalent time across several timezones at once.
- When converting a date to a timestamp, make sure you explicitly select which timezone the entered date and time belongs to.
- The ISO 8601 (UTC) format can be parsed directly by most programming languages and databases, making it a handy reference when searching logs or designing an API.
- Click "Fill current time" to instantly populate the field with the current time from the browser's Date.now().
Frequently Asked Questions
Side Note — Why do computers count time in seconds?
Humans express dates and times as a combination of year, month, day, and time of day, such as "July 12, 2026, 5:08 PM." For a computer, however, this format is inconvenient: it has to account for complex rules like leap years, timezones, and daylight saving time, and even computing the gap between two dates becomes a cumbersome operation. The solution devised was to represent time as a single number: the number of seconds elapsed since some reference moment. This is exactly what a Unix timestamp does.
The biggest advantage of representing time as a single integer is that comparing and computing differences between dates reduces to simple arithmetic. Finding "how many seconds apart are these two events" is just a matter of subtracting one timestamp from another, with no need to worry about leap years or varying month lengths. Thanks to this simplicity, the format was adopted not only by Unix-like systems but also by Windows, databases, and the internal representations of many programming languages, making it a de facto global standard.
On the other hand, this design of a single, timezone-independent number means that timezone conversion only becomes necessary once a human needs to read the value. The very same timestamp can look like the middle of the night in Tokyo and the previous afternoon in New York, depending on which timezone it is displayed in. Many of the confusing "the time is off" bugs encountered while investigating logs or debugging API integrations trace back to exactly this kind of overlooked timezone conversion.