Unix timestamp converter
Convert between Unix timestamps and human-readable dates — in both directions. Edit either input and the other updates automatically.
Enter a Unix timestamp (seconds or milliseconds) on the left, or pick a date and time on the right. Both fields stay in sync. Click Now to load the current time.
Unix timestamp converter
Auto-detect: —
Seconds or milliseconds — auto-detected
Interpreted as your local timezone
Formatted output
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About Unix timestamps
Unix time counts seconds since the Unix epoch — midnight, 1 January 1970, UTC. It is defined in POSIX and used by virtually every operating system, database, and programming language. Because it is a simple integer with no timezone information embedded, it is unambiguous and trivially comparable. Storing timestamps as integers also avoids the many subtleties of timezone-aware date types.
Millisecond precision (multiplied by 1,000) became common as JavaScript's
Date.now() returns milliseconds, and many modern APIs
followed. When in doubt, check the number of digits: 10 digits is seconds (current), 13 digits
is milliseconds (current). The year 2038 problem affects systems that store Unix time as a
signed 32-bit integer — it will overflow on 19 January 2038. Modern systems use 64-bit integers
and are unaffected.
About this tool
Enter a Unix timestamp (seconds or milliseconds) to see it formatted as ISO 8601, RFC 2822, UTC, local time, and relative time. Or pick a date and time to get the Unix timestamp back. Seconds vs milliseconds are auto-detected: any value above 10 billion is treated as milliseconds. Everything runs client-side — nothing is sent to a server.
Frequently asked questions
What is a Unix timestamp?
A Unix timestamp (also called epoch time or POSIX time) is the number of seconds — or milliseconds — that have elapsed since 00:00:00 UTC on 1 January 1970, not counting leap seconds. It is the most common way to represent a point in time in software because it is unambiguous, timezone-independent, and trivially stored as an integer. Most programming languages and databases have built-in support for Unix timestamps.
How do I tell seconds apart from milliseconds?
Current Unix time in seconds is a 10-digit number (around 1,750,000,000). In milliseconds it is a 13-digit number (around 1,750,000,000,000). This tool auto-detects: any value larger than 9,999,999,999 is treated as milliseconds. If your timestamp is in microseconds (16 digits) or nanoseconds (19 digits), divide it before pasting here.
What is ISO 8601 format?
ISO 8601 is an international standard for date and time representations. The most common form is `2024-01-15T12:30:00.000Z` where the trailing `Z` means UTC. This format is used in JSON APIs, HTML date attributes, log files, and most modern databases. It sorts correctly as a string because the most-significant component (year) comes first.
What is RFC 2822 format?
RFC 2822 is the date format defined for email headers — for example, `Mon, 15 Jan 2024 12:30:00 +0000`. It is still widely used in email, HTTP headers (the `Date:` header), and RSS/Atom feeds. JavaScript's `Date.prototype.toUTCString()` returns an RFC 2822-compatible string.
What does "relative time" mean?
Relative time expresses a timestamp as a human-readable duration from now — for example "3 hours ago" or "2 days from now". It is useful for displaying timestamps in UIs where the exact date is less important than how recent the event was. The precision decreases as the distance from now increases: within a minute it says "just now", then minutes, hours, days, months, and years.