Type a date/time in any format — ISO 8601, RFC 2822, a Unix timestamp in seconds or milliseconds, and more — and it is auto-detected and shown simultaneously as ISO 8601, RFC 2822, Unix timestamps, local time, and more. Pick a UTC offset to also compute the ISO 8601 representation for that timezone.
ISO 8601 is the international standard format for dates and times, e.g. "YYYY-MM-DDTHH:mm:ss.sssZ" — year-month-day and hour:minute:second separated by T, followed by UTC (Z) or a timezone offset such as +09:00. It is widely used in logs, API responses, and databases because it is unambiguous to both humans and machines.
A Unix timestamp counts seconds (or milliseconds) since 1970-01-01T00:00:00Z. This tool auto-detects purely numeric input by digit count — 10 to 11 digits is treated as seconds, 13 digits as milliseconds. To render ISO 8601 at a chosen offset, it adds the offset (in minutes) to the UTC instant, formats the result as a "wall clock" time, and appends the original offset as a suffix — a calculation that stays correct regardless of the browser's own local timezone.
RFC 2822 (common in email headers) and the HTTP Date header use a format like "Tue, 15 Jan 2024 09:30:00 GMT". JavaScript's toUTCString() produces this format, and Date.parse() can read both it and ISO 8601, so this single tool can convert dates coming from many different sources — log files, API headers, database dumps, and more.