Time Validation Regex: 24-Hour Format (HH:MM)

Validate time in 24-hour format (HH:MM) with proper hour and minute range validation using regex.

Pattern Breakdown

^([01]\d|2[0-3]):[0-5]\d$

Components

Detailed Breakdown

• ([01]\d|2[0-3]) - Hour alternation:
  • [01]\d - Hours 00-19 (first digit 0 or 1, second digit 0-9)
  • 2[0-3] - Hours 20-23 (first digit 2, second digit 0-3)
• [0-5]\d - Minutes: 00-59
  • [0-5] - First digit 0-5
  • \d - Second digit 0-9

Examples

Valid:

• 00:00 (midnight)
• 12:00 (noon)
• 23:59 (one minute before midnight)
• 09:30
• 15:45
• 01:05

Invalid:

• 24:00 (invalid hour, should be 00:00)
• 23:60 (invalid minutes)
• 9:30 (hour not zero-padded)
• 23:5 (minutes not zero-padded)
• 23-30 (wrong separator)
• 25:00 (invalid hour)

Implementation

JavaScript

const timeRegex = /^([01]\d|2[0-3]):[0-5]\d$/;
timeRegex.test('23:59'); // true
timeRegex.test('00:00'); // true
timeRegex.test('12:30'); // true
timeRegex.test('24:00'); // false (invalid hour)
timeRegex.test('23:60'); // false (invalid minutes)

Python

import re
time_regex = r'^([01]\d|2[0-3]):[0-5]\d$'
bool(re.match(time_regex, '23:59'))  # True
bool(re.match(time_regex, '00:00'))  # True
bool(re.match(time_regex, '24:00'))  # False (invalid hour)

Go

timeRegex := regexp.MustCompile(`^([01]\d|2[0-3]):[0-5]\d$`)
timeRegex.MatchString("23:59") // true
timeRegex.MatchString("00:00") // true
timeRegex.MatchString("24:00") // false (invalid hour)

Limitations

1. No seconds: Only validates HH:MM, not HH:MM:SS
2. No timezone: Doesn't include timezone information
3. Format only: Validates format, not time logic
4. No AM/PM: 24-hour format only
5. Fixed format: Requires zero-padding

When to Use

• 24-hour time input validation
• Military time format
• International time formats
• Database time field validation
• When you need unambiguous time format

For production, consider:

• Adding seconds support: ^([01]\d|2[0-3]):[0-5]\d:[0-5]\d$
• Timezone handling if needed
• Combining with time parsing for full validation
• Supporting optional zero-padding