Home Postcode finder SA Stephenston Stephenston postcode SA Stephenston is a locality in South Australia covered by postcode 5433. Postcode 5433 State or territory South Australia (SA) Region SA Outer Suburbs Add a free Stephenston business listing Be the first listing in Stephenston Common questionsWhat is the postcode for Stephenston?Stephenston, SA has the postcode 5433.What state is Stephenston in?Stephenston is in South Australia (SA).Does postcode 5433 cover more than one suburb?Yes. Postcode 5433 covers 6 localities, so the postcode alone does not identify Stephenston. Browse other postcodes in South Australia, or widen the search to every Australian postcode.