MAC Address Regex

Developer

Regular expression

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

Pattern breakdown

Part	Meaning
`Anchor or context`	Use anchors when you need whole-string validation.
`Main token`	The core token sequence describes the accepted text shape.
`Character class`	Character classes limit which characters are valid.
`Quantifier`	Quantifiers control how many characters or groups are accepted.
`Flags`	Use language-specific flags such as i, m, or u only when needed.

Should match

aa:bb:cc:dd:ee:ff

Should not match

aa:bb
not matching sample
aa:bb:cc:dd:ee:ff invalid
aa:bbaa:bb:cc:dd:ee:ff

Test cases

Input	Expected	Why it matters
`aa:bb:cc:dd:ee:ff`	Match	Representative valid input for this pattern.
`aa:bb`	No match	Common invalid or boundary input.
`(empty string)`	No match	Common invalid or boundary input.
`not matching sample`	No match	Common invalid or boundary input.
`aa:bb:cc:dd:ee:ff invalid`	No match	Common invalid or boundary input.
`aa:bbaa:bb:cc:dd:ee:ff`	No match	Common invalid or boundary input.

JavaScript

const re = /^(?:[0-9A-Fa-f]{2}[:-]){5}[0-9A-Fa-f]{2}$/;
re.test(input);

Python

import re
bool(re.search(r"^(?:[0-9A-Fa-f]{2}[:-]){5}[0-9A-Fa-f]{2}$", text))

PHP

$ok = preg_match('/^(?:[0-9A-Fa-f]{2}[:-]){5}[0-9A-Fa-f]{2}$/', $value) === 1;

Java

Pattern pattern = Pattern.compile("^(?:[0-9A-Fa-f]{2}[:-]){5}[0-9A-Fa-f]{2}$");
pattern.matcher(value).find();

Go

re := regexp.MustCompile(`^(?:[0-9A-Fa-f]{2}[:-]){5}[0-9A-Fa-f]{2}$`)
ok := re.MatchString(value)

Notes and production use

MAC Address regex is useful as a practical starting point. Test it against your real input, avoid using it as the only security control, and prefer a parser when the format has complex grammar.

Performance tip: avoid running complex regular expressions repeatedly on very large untrusted strings without limits. Prefer anchored validation patterns, cap input length before matching, and use a parser when the target format has nested grammar.

MAC Address