Unix Timestamp Converter
Turn a Unix epoch timestamp into a readable date in UTC and your local time zone — or pick a date and get the epoch back. Seconds and milliseconds are detected automatically.
A Unix timestamp — also called epoch time — is simply the number of seconds since 00:00:00 UTC on 1 January 1970. It's the most common way computers store an instant in time, because a single integer is compact, sorts correctly and carries no time‑zone ambiguity. This converter goes both ways: paste an epoch value to see the UTC string, your local time and an ISO 8601 timestamp, or pick a date and read back the epoch in both seconds and milliseconds.
The tricky part is that some systems store seconds (a 10‑digit number today) and others store milliseconds (13 digits). The tool auto‑detects by length — 12 or more digits is treated as milliseconds — so you rarely have to think about it. The Now button drops in the current moment using your device clock, which is handy for testing.
The same epoch value maps to a single instant everywhere on Earth, but it displays differently depending on time zone. That's why this tool always shows the UTC form and your browser's local time — so you can see exactly what a log line or database field really means.
Epoch timestamps show up constantly in APIs and tokens. A JWT's iat (issued‑at) and exp (expiry) claims are Unix seconds, and log files, cookies and TLS certificates all use epoch time. If you're inspecting an API response, the JSON Formatter makes those raw numbers easier to spot. Curious where those requests travel and how they're timed? Our guide on HTTP vs HTTPS is a good primer on the traffic behind the timestamps.
Everything runs locally with your browser's built‑in Date object and your own clock — no network calls, no tracking. It even works offline once the page has loaded.
Frequently asked questions
What is a Unix timestamp?
A Unix timestamp (also called 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 simple, time‑zone‑independent way to represent a moment in time and is used throughout programming and databases.
How does the tool tell seconds from milliseconds?
It auto‑detects by digit count. A timestamp with 12 or more digits is treated as milliseconds; anything shorter is treated as seconds. Present‑day second timestamps have 10 digits, while millisecond timestamps have 13, so the detection is reliable for modern dates.
What is the year 2038 problem?
Systems that store Unix time in a signed 32‑bit integer overflow at 03:14:07 UTC on 19 January 2038, wrapping around to a negative number. Modern 64‑bit systems and JavaScript, which uses a 64‑bit float for milliseconds, are not affected.
Does this converter work offline and privately?
Yes. All conversions use your browser's built‑in Date object and your device's own clock and time zone. Nothing is sent to a server, so it works offline and keeps your data private.
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