Unix Timestamp Converter
Convert Unix timestamps in seconds or milliseconds to UTC and local dates, or convert ISO/date strings to epoch values.
Formatted Date Representations
| ISO 8601 (UTC) | — |
|---|---|
| RFC 7231 / UTC String | — |
| Browser Local Time | — |
About Unix Epoch Timestamps
A Unix timestamp counts the elapsed time since 1970-01-01T00:00:00Z (the Unix Epoch) excluding leap seconds. Standard 10-digit integers (such as 1730112000) represent seconds, whereas 13-digit integers (such as 1730112000000) represent milliseconds—the native precision of JavaScript's Date.now() and RFC 9562 UUID v7 headers.
Automatic Unit Detection
Leave the unit selector on Auto-detect to automatically distinguish 10-digit second timestamps from 13-digit millisecond timestamps, including negative values for dates prior to 1970.
ISO 8601 & RFC 7231 Output
Simultaneously inspect the UTC ISO 8601 string, HTTP header RFC 7231 format, your browser's local timezone offset, and human-readable relative time deltas.
Bidirectional Date Parsing
Paste any ISO 8601 timestamp or date string (e.g., 2026-10-28T12:00:00Z) to compute both the 10-digit Unix seconds and 13-digit Unix milliseconds immediately.
Frequently Asked Questions
What is the Year 2038 (Y2K38) problem?
Legacy systems that store Unix timestamps in a signed 32-bit integer overflow after 2,147,483,647 seconds (2038-01-19T03:14:07Z). Modern 64-bit operating systems, databases, and JavaScript's 53-bit safe integer Date representation support timestamps millions of years into the future.
Why do JWT tokens use 10-digit timestamps while JavaScript uses 13 digits?
RFC 7519 defines JWT NumericDate claims (exp, iat, nbf) in seconds since the epoch, whereas JavaScript's Date.now() returns milliseconds. Divide by 1000 (Math.floor(Date.now() / 1000)) when generating JWT claims in JavaScript.