Regex for Date (YYYY-MM-DD) — Pattern Explained with Examples

This regex validates dates in the ISO-inspired YYYY-MM-DD format. It checks that the year is four digits, the month is between 01 and 12, and the day is between 01 and 31. This pattern is useful for form validation, data import sanitization, and API input processing where date format consistency is required.

The Pattern

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

Pattern Breakdown

Matches

• 2024-01-15
• 1999-12-31
• 2023-06-01
• 2000-02-28
• 2024-07-04

Does NOT Match

• 2024/01/15 — uses slashes instead of hyphens
• 2024-13-01 — month 13 is invalid
• 2024-01-32 — day 32 is invalid
• 24-01-15 — year is only 2 digits
• 2024-1-1 — missing leading zeros
• 2024-00-01 — month 00 is invalid
• Feb 15 2024 — non-numeric format
• 2024-01- — incomplete date

Language Examples

JavaScript

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

console.log(dateRegex.test('2024-01-15'));  // true
console.log(dateRegex.test('2024-13-01'));  // false
console.log(dateRegex.test('2024-01-32'));  // false

// Extract parts with capture groups
const match = '2024-01-15'.match(dateRegex);
if (match) {
  console.log(`Year: ${match[0]}, Month: ${match[1]}, Day: ${match[2]}`);
}

Python

import re

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

print(bool(re.match(date_regex, '2024-01-15')))  # True
print(bool(re.match(date_regex, '2024-13-01')))  # False
print(bool(re.match(date_regex, '2024-01-32')))  # False

# Extract parts
match = re.match(date_regex, '2024-01-15')
if match:
    year, month, day = match.group(0), match.group(1), match.group(2)
    print(f'{year}-{month}-{day}')

Common Pitfalls

1. February 29 passes — The regex accepts 2024-02-29 (valid leap year) but also 2023-02-29 (invalid — 2023 is not a leap year). Date validation requires a separate calendar check.

2. Leap years not handled — The regex does not distinguish between common and leap years. Use a date library like date-fns or Python’s datetime for full validation.

3. Separator flexibility — This pattern only accepts hyphens. Users may input slashes, dots, or spaces. Consider accepting multiple separators if needed.

4. Leading zeros required — 2024-1-1 fails because single-digit months/days are not allowed. Decide whether leading zeros are mandatory for your use case.

Real-World Use Cases

• Form validation: Accepting user birth dates or event dates in a standardized format
• API input sanitization: Ensuring date parameters conform to ISO 8601 calendar date format
• Data import processing: Validating date columns in CSV or spreadsheet uploads

FAQ