Regular Expressions Cookbook

4.15. Validate Canadian Postal Codes

Problem

You want to check whether a string is a Canadian postal code.

Solution

^(?!.*[DFIOQU])[A-VXY][0-9][A-Z]●[0-9][A-Z][0-9]$

Regex options: None

Regex flavors: .NET, Java, JavaScript, PCRE, Perl, Python, Ruby

Discussion

The negative lookahead at the beginning of this regular expression prevents D, F, I, O, Q, or U anywhere in the subject string. The ‹[A-VXY]› character class further prevents W or Z as the first character. Aside from those two exceptions, Canadian postal codes simply use an alternating sequence of six alphanumeric characters with a space in the middle. For example, the regex will match K1A 0B1, which is the postal code for Canada Post’s Ottawa headquarters.

See Also

Recipes 4.14, 4.16, and 4.17