ISO 8601 Parser

Parsed as an ISO 8601 date: 2024-02-29.

How it works

• Matched the string against the strict ISO 8601 grammar for dates, times, durations and intervals.
• Validated every component against the proleptic Gregorian calendar, including leap years and ISO week boundaries.
• Returned the components, a normalised form, and the derived weekday, week and ordinal fields.

• ISO weekday 4 (Thursday).
• ISO week 9 of week-year 2024.
• Day 60 of 2024.

Methodology

1. Match the string against strict ISO 8601 grammars for calendar, ordinal and week dates, times, durations and intervals.
2. Validate every numeric component — month lengths, leap years, ordinal day, ISO week number and offset — before accepting it.
3. Normalise the value and derive the ISO weekday, week number and ordinal day from proleptic-Gregorian arithmetic.

Usage

1. Enter an ISO 8601 date, time, date-time, duration or interval.
2. Run the parser.
3. Read the normalised form, the components and the derived weekday, week and ordinal fields.

Examples

These are examples, not current values: they use fixed inputs, while the interactive tool computes live results in your browser.

Calendar date

{
  "value": "2024-02-29"
}

Date-time with offset

{
  "value": "2026-07-15T12:34:56.789+05:45"
}

Ordinal date

{
  "value": "2026-060"
}

Week date

{
  "value": "2026-W03-5"
}

Duration

{
  "value": "P1Y2M3DT4H5M6S"
}

Interval with a duration

{
  "value": "2026-01-01T00:00:00Z/P1M"
}

Limitations

Why strict parsing matters

Lenient parsers silently accept impossible dates or ambiguous separators. This parser only accepts the extended ISO 8601 forms and rejects anything it cannot validate component by component.