Unix Timestamp Converter
Convert epoch time to a readable date, or a date back to a timestamp — in your local timezone or UTC. Auto-detects seconds vs. milliseconds.
By Alex van den Berg · Last reviewed · How we test our tools
Timestamp → Date
Date → Timestamp
What is Unix time?
Unix time (also called epoch time or POSIX time) counts seconds elapsed since 00:00:00 UTC on 1 January 1970 — the "epoch". It was chosen by early Unix developers as an arbitrary but convenient reference point. Because it's a single ever-increasing integer, it sidesteps every ambiguity that human date formats create: no timezone, no calendar system, no daylight saving confusion. That's why databases, log files, JWT tokens, and APIs almost universally store time this way internally, converting to a readable date only for display.
Leap seconds are technically not counted in Unix time — POSIX systems handle them by repeating or skipping a second, which is a minor detail engineers rarely encounter in practice.
Notable timestamps
| Timestamp (seconds) | UTC date | Significance |
|---|---|---|
| 0 | 1 Jan 1970, 00:00:00 | The Unix epoch itself |
| 1000000000 | 9 Sep 2001, 01:46:40 | "Billennium" — widely celebrated by developers |
| 1234567890 | 13 Feb 2009, 23:31:30 | Ascending digit sequence, a popular test value |
| 1600000000 | 13 Sep 2020, 12:26:40 | Round 1.6 billion mark |
| 2147483647 | 19 Jan 2038, 03:14:07 | Maximum signed 32-bit int — the "Year 2038 problem" |
Frequently Asked Questions
What is a Unix timestamp?
A Unix timestamp (or epoch time) is the number of seconds that have elapsed since 00:00:00 UTC on 1 January 1970, not counting leap seconds. It is a single integer that unambiguously represents a moment in time regardless of timezone, which is why databases, APIs, and log files use it internally.
Why does my timestamp have 13 digits instead of 10?
A 10-digit number is seconds since the epoch; a 13-digit number is milliseconds since the epoch (seconds × 1,000). JavaScript's Date.now() and many web APIs return milliseconds, while Unix system tools and many databases use seconds. This converter auto-detects which unit you pasted based on digit count.
What is the Year 2038 problem?
Systems that store Unix time as a signed 32-bit integer will overflow at 03:14:07 UTC on 19 January 2038, wrapping to a negative number that represents the year 1901. This mainly affects older embedded systems and legacy C code compiled for 32-bit time_t. Modern 64-bit systems store timestamps as 64-bit integers, pushing the overflow date billions of years into the future.
Does a Unix timestamp include timezone information?
No — a Unix timestamp is always a count of seconds since the epoch in UTC. It has no inherent timezone. The timezone only enters the picture when you convert that number into a human-readable date, which is why the same timestamp displays a different clock time in London versus Tokyo. Use the timezone selector above to see both.
Can Unix timestamps be negative?
Yes. A negative Unix timestamp represents a date before 1 January 1970. Most modern systems handle negative timestamps correctly back to the limits of their date libraries, but very old dates (pre-1900) can behave inconsistently across platforms due to historical calendar reforms.
Sources & further reading
- IEEE Std 1003.1 (POSIX) — the formal definition of "seconds since the Epoch". pubs.opengroup.org
- MDN Web Docs — "Date.now()" and "Date" object reference. developer.mozilla.org