Question 1

What is a Unix timestamp?

Accepted Answer

A Unix timestamp (also called epoch time or POSIX time) is the number of seconds since January 1, 1970, 00:00:00 UTC. It's the standard way to represent time in programming — simple to store (one integer), unambiguous, timezone-independent, and easy to do arithmetic with.

Question 2

Why does epoch start at January 1, 1970?

Accepted Answer

January 1, 1970 (Unix Epoch) was chosen arbitrarily when UNIX was being developed in the early 1970s. It was a recent, round date that provided a convenient epoch for time calculations on the systems of that era.

Question 3

What is the Year 2038 problem?

Accepted Answer

32-bit signed integers can store Unix timestamps up to January 19, 2038 at 03:14:07 UTC. After that, they overflow to negative values. Modern systems use 64-bit timestamps which extend the range to year 292,277,026,596 — effectively solving the problem.

Question 4

What is the difference between Unix time in seconds vs milliseconds?

Accepted Answer

Most Unix timestamps are in seconds. JavaScript's Date.now() returns milliseconds (multiply by 1000 from seconds). Python's time.time() returns seconds as a float. Node.js uses milliseconds by default. Always check which unit a system expects to avoid off-by-1000 bugs.

Question 5

How do I convert a Unix timestamp in different languages?

Accepted Answer

JavaScript: new Date(timestamp * 1000). Python: datetime.fromtimestamp(timestamp). Go: time.Unix(timestamp, 0). Java: Instant.ofEpochSecond(timestamp). SQL: FROM_UNIXTIME(timestamp) in MySQL, TO_TIMESTAMP(timestamp) in PostgreSQL.

Question 6

How do I convert a Unix timestamp to a date?

Accepted Answer

Paste your Unix timestamp (seconds since January 1, 1970 UTC) above and click Convert. The tool displays the date and time in both UTC and your local timezone. For JavaScript: new Date(timestamp * 1000). For Python: datetime.fromtimestamp(timestamp). For negative timestamps, dates before 1970 are supported.

Question 7

What is the Unix timestamp for today?

Accepted Answer

The current Unix timestamp updates in real time above — it shows the current seconds since January 1, 1970 UTC (the Unix epoch). The timestamp for January 1, 2000 was 946684800; for January 1, 2030 it will be 1893456000. Unix timestamps are timezone-independent, which makes them ideal for storing and comparing dates across systems.

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