What is a Unix timestamp?
A Unix timestamp is the number of seconds elapsed since January 1, 1970 00:00:00 UTC — called the Unix Epoch. It is the universal language of time in computing: databases, APIs, log files, and distributed systems all use it to store and exchange dates without timezone ambiguity.
The timestamp is a single integer — compact, sortable, and timezone-agnostic. Converting it to a human-readable date depends on the viewer's local timezone, which is why this tool shows both UTC and your local time.
Seconds vs milliseconds
Unix timestamps come in two flavors depending on the platform:
| Format | Digits (circa 2026) | Common in |
|---|---|---|
| Seconds | 10 digits (~1741000000) | Unix/Linux, databases, most APIs |
| Milliseconds | 13 digits (~1741000000000) | JavaScript Date.now(), Java, Android |
A quick way to tell: if the timestamp is 13 digits, it's milliseconds. If it's 10 digits, it's seconds. In JavaScript, Date.now() returns milliseconds; Math.floor(Date.now() / 1000) gives seconds.
Notable Unix timestamps
| Timestamp | Meaning |
|---|---|
| 0 | Unix Epoch — January 1, 1970 00:00:00 UTC |
| 1000000000 | September 9, 2001 01:46:40 UTC |
| 1234567890 | February 13, 2009 23:31:30 UTC (a famous milestone) |
| 1700000000 | November 14, 2023 |
| 2147483647 | January 19, 2038 — 32-bit overflow (Year 2038 problem) |
| 2000000000 | May 18, 2033 |
Working with timestamps in code
JavaScript
Date.now() // ms since epoch
Math.floor(Date.now() / 1000) // seconds
new Date(1741000000 * 1000) // timestamp → Date
new Date('2026-03-01').getTime() / 1000 // date → timestamp
Python
import time, datetime
time.time() # current timestamp (float)
datetime.datetime.fromtimestamp(ts) # local time
datetime.datetime.utcfromtimestamp(ts) # UTC