How does WordPress generate URL slugs?

Is there a page somewhere that details exactly how WordPress generates slugs for URLs? I’m writing a script that needs to generate URL slugs identical to the ones WordPress generates.


As per @SinisterBeard’s very valid comment to the question already a couple of years back now, this answer has long been outdated and the mentioned function(s) hence been replaced by a newer API:

See wp_unique_post_slug.


Off the bat, I can’t give you a page/tutorial/documentation on how WP slugs are generated, but take a look at the sanitize_title() function.

Don’t get a wrong impression by the function name, it is not meant to sanitize a title for further usage as a page/post title. It takes a title string and returns it to be used in a URL:

  • strips HTML & PHP
  • strips special chars
  • converts all characters to lowercaps
  • replaces whitespaces, underscores and periods by hyphens/dashes
  • reduces multiple consecutive dashes to one

There might be edge cases where the core does something additional (you’d have to look at the source to verify that sanitize_title() will always suffice in generating exactly the same you expect), but this should cover at least 99%, if not all, cases.

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