Date Validation Regex: YYYY-MM-DD Format

Validate dates in ISO 8601 date format (YYYY-MM-DD) with proper month and day range validation using regex.

Pattern Breakdown

^\d{4}-(0[1-9]|1[0-2])-(0[1-9]|[12]\d|3[01])$

Components

Detailed Breakdown

• \d{4} - Year: exactly 4 digits (0000-9999)
• (0[1-9]|1[0-2]) - Month alternation:
  • 0[1-9] - Months 01-09
  • 1[0-2] - Months 10-12
• (0[1-9]|[12]\d|3[01]) - Day alternation:
  • 0[1-9] - Days 01-09
  • [12]\d - Days 10-29
  • 3[01] - Days 30-31

Examples

Valid:

• 2024-03-15
• 2024-01-01
• 2024-12-31
• 2024-02-29 (format valid, but may not be valid date)
• 0000-01-01 (format valid)

Invalid:

• 24-03-15 (year too short)
• 2024-3-15 (month not zero-padded)
• 2024-03-5 (day not zero-padded)
• 2024-13-15 (invalid month)
• 2024-03-32 (invalid day)
• 2024/03/15 (wrong separator)
• 03-15-2024 (wrong order)

Implementation

JavaScript

const dateRegex = /^\d{4}-(0[1-9]|1[0-2])-(0[1-9]|[12]\d|3[01])$/;
dateRegex.test('2024-03-15'); // true
dateRegex.test('2024-12-31'); // true
dateRegex.test('2024-13-15'); // false (invalid month)
dateRegex.test('2024-03-32'); // false (invalid day)

Python

import re
date_regex = r'^\d{4}-(0[1-9]|1[0-2])-(0[1-9]|[12]\d|3[01])$'
bool(re.match(date_regex, '2024-03-15'))  # True
bool(re.match(date_regex, '2024-12-31'))  # True
bool(re.match(date_regex, '2024-13-15'))  # False (invalid month)

Go

dateRegex := regexp.MustCompile(`^\d{4}-(0[1-9]|1[0-2])-(0[1-9]|[12]\d|3[01])$`)
dateRegex.MatchString("2024-03-15") // true
dateRegex.MatchString("2024-12-31") // true
dateRegex.MatchString("2024-13-15") // false (invalid month)

Limitations

1. No leap year validation: Accepts 2024-02-30 (format valid, date invalid)
2. No month-specific day validation: Accepts 2024-04-31 (April has 30 days)
3. No year range validation: Accepts years like 0000 or 9999
4. Format only: Validates format, not actual date validity
5. No time component: Date only, no time

When to Use

• ISO 8601 date format validation
• Database date input (YYYY-MM-DD)
• API date parameters
• Date picker input validation
• When you need zero-padded dates

For production, consider:

• Additional validation for actual date validity (leap years, month lengths)
• Using date parsing libraries to verify dates
• Validating year ranges for your use case
• Combining with date object validation