What is a Unix timestamp?
A Unix timestamp counts the seconds (sometimes milliseconds) elapsed since the Unix epoch — midnight UTC on January 1, 1970. It's a compact, timezone-free way to store a point in time, which is why databases, logs, and APIs use it so often instead of a formatted date string.
Seconds vs. milliseconds
A 10-digit timestamp like 1700000000 is almost always seconds. A 13-digit timestamp like 1700000000000 is milliseconds — JavaScript's Date.now() returns this form. This tool auto-detects which one you pasted based on digit count.
Frequently asked questions
Does a Unix timestamp include a timezone?
No. A timestamp is just a count of seconds — it's timezone-independent by definition. The date/time shown when you convert it reflects your browser's local timezone; the underlying number is the same everywhere in the world.
What happens after the year 2038?
Systems that store a timestamp as a signed 32-bit integer overflow on January 19, 2038 — the "Year 2038 problem." Most modern systems use 64-bit integers and aren't affected, but it's worth knowing if you're working with older embedded or database systems.
Is my data uploaded when I use this tool?
No. Conversion happens instantly in your browser using JavaScript's built-in Date object — nothing is sent to a server.