Regex for MAC Address — Pattern Explained with Examples

In this tutorial, you'll learn about Regex for MAC Address. We cover key concepts, practical examples, and best practices to help you understand and apply this topic effectively.

MAC (Media Access Control) address validation is needed in network tools, device enrollment systems, and hardware inventory management. A MAC address is a 48-bit identifier typically written as 6 pairs of hexadecimal digits separated by colons or hyphens, or as a continuous 12-character hex string.

The Pattern

/^([0-9A-Fa-f]{2}[:-]){5}([0-9A-Fa-f]{2})$/

For the continuous no-separator format:

/^[0-9A-Fa-f]{12}$/

Pattern Breakdown

Matches

• 00:1A:2B:3C:4D:5E
• 00-1A-2B-3C-4D-5E
• AA:BB:CC:DD:EE:FF
• a1:b2:c3:d4:e5:f6
• 001A2B3C4D5E

Does NOT Match

• 00:1A:2B:3C:4D (only 5 groups)
• 00:1A:2B:3C:4D:5E:6F (7 groups)
• 00:1A:2B:3C:4D:GH (invalid hex characters)
• 00:1A:2B:3C:4D:5 (odd number of hex digits in last group)
• 001A2B3C4D5 (only 11 hex characters)

Language Examples

JavaScript

const macRegex = /^([0-9A-Fa-f]{2}[:-]){5}([0-9A-Fa-f]{2})$/;
const macContinuousRegex = /^[0-9A-Fa-f]{12}$/;
console.log(macRegex.test('00:1A:2B:3C:4D:5E')); // true
console.log(macRegex.test('00:1A:2B:3C:4D'));     // false

Python

import re
pattern = r'^([0-9A-Fa-f]{2}[:-]){5}([0-9A-Fa-f]{2})$'
print(bool(re.match(pattern, '00:1A:2B:3C:4D:5E')))  # True
print(bool(re.match(pattern, '00:1A:2B:3C:4D')))      # False

Go

package main

import (
	"fmt"
	"regexp"
)

func main() {
	re := regexp.MustCompile(`^([0-9A-Fa-f]{2}[:-]){5}([0-9A-Fa-f]{2})$`)
	fmt.Println(re.MatchString("00:1A:2B:3C:4D:5E"))  // true
	fmt.Println(re.MatchString("00:1A:2B:3C:4D"))       // false
}

Common Pitfalls

• The multicast vs unicast bit (second hex character's least significant bit) determines address type — this pattern does not validate that bit
• EUI-64 identifiers are 8 bytes (16 hex digits) long, not 6 bytes — a different pattern is needed for IPv6-derived MACs
• The broadcast address FF:FF:FF:FF:FF:FF is valid by the pattern but may need special handling in business logic
• Case sensitivity can cause duplicate records — normalize to uppercase or lowercase before storage
• Leading zeros in each pair are significant and must be preserved

Real-World Use Cases

• Device provisioning portals — validate MAC addresses during network device enrollment and registration
• Inventory management — scan and verify hardware MAC addresses against purchase records or asset tags
• DHCP server configuration — validate MAC address entries for static IP reservations in DHCP lease files

FAQ

Related Patterns

Regex for IPv4 Address Regex for IPv6 Address