ISO 8601 Parser / Validator
Parse and validate ISO 8601 strings — dates, datetimes, durations, week dates, ordinal dates, and intervals.
Examples (click to load)
About this tool
ISO 8601 is the international standard for representing dates, times, and durations. It specifies a big-endian order (largest unit first: year, then month, then day) with components separated by hyphens for dates and colons for times: 2024-03-15T14:30:00. This ordering sorts correctly as a string, unlike common regional formats like MM/DD/YYYY (US) or DD/MM/YYYY (European), which cause frequent international ambiguity.
The timezone component is critical for unambiguous timestamps. Z at the end indicates UTC (Zulu time). An explicit offset like +09:00 or -05:30 indicates a fixed offset from UTC. A timestamp without a timezone component is ambiguous — it does not specify a unique moment in time. RFC 3339 is a stricter profile of ISO 8601 used in internet protocols, requiring a timezone designator and mandating the T separator.
ISO 8601 also defines duration notation: P1Y2M3DT4H5M6S means 1 year, 2 months, 3 days, 4 hours, 5 minutes, and 6 seconds. This format is used in APIs, XML schemas, and many calendar formats. In application development, always store timestamps in UTC and include explicit timezone information. When displaying times to users, convert from UTC to their local timezone in the presentation layer only.