Home Postcode finder SA Willoughby Willoughby postcode SA Willoughby is a locality in South Australia covered by postcode 5222. Postcode 5222 State or territory South Australia (SA) Region Sa Subs Near 2 Add a free Willoughby business listing Be the first listing in Willoughby Common questionsWhat is the postcode for Willoughby?Willoughby, SA has the postcode 5222.What state is Willoughby in?Willoughby is in South Australia (SA).Does postcode 5222 cover more than one suburb?Yes. Postcode 5222 covers 17 localities, so the postcode alone does not identify Willoughby. Browse other postcodes in South Australia, or widen the search to every Australian postcode.