Common use cases
- ✓CSV and import format checks
- ✓Form input normalization
- ✓Log and filename date validation
JavaScript-compatible regex reference
YYYY-MM-DD Date Regex Pattern & Tester
Validate the common four-digit-year, two-digit-month, two-digit-day shape while constraining months to 01–12 and days to 01–31. The pattern is useful for format validation, but calendar semantics such as February 30 still require a real date parser.
Pattern
^\d{4}-(?:0[1-9]|1[0-2])-(?:0[1-9]|[12]\d|3[01])$Flags: none
Live test vectors
Test the ISO date (YYYY-MM-DD) regex
Enter one value per line. Each line is tested against the whole-string pattern using the browser JavaScript RegExp engine.
PASS
2026-08-17PASS
2000-01-01PASS
1999-12-31FAIL
2026-8-17FAIL
2026-13-01FAIL
2026-00-10FAIL
17-08-2026Quick answer
Use regex when you need to enforce the YYYY-MM-DD text shape. Use a date parser after the regex if you must reject impossible calendar dates such as 2026-02-31.
Pitfalls and limitations
- !A regex that limits days to 01–31 still cannot know how many days are in a specific month.
- !Leap-year rules are better handled by a date library or runtime parser.
- !Do not confuse a date-only format with a complete ISO 8601 timestamp including time and timezone.
Known-valid examples
2026-08-172000-01-011999-12-31Known-invalid examples
2026-8-172026-13-012026-00-1017-08-2026Continue testing and debugging
Frequently asked questions
Does this regex reject February 31?
No. It validates the numeric YYYY-MM-DD format and broad month/day ranges. Calendar-validity checks belong in a date parser.
Why require two-digit months and days?
The target format is fixed-width YYYY-MM-DD, so January 5 is written 2026-01-05 rather than 2026-1-5.
Can I use this for full ISO 8601 timestamps?
No. Timestamps add time, optional fractional seconds, and timezone information, so they require a different pattern or, preferably, an ISO date-time parser.