Home Postcode finder SA Biggs Flat Biggs Flat postcode SA Biggs Flat is a locality in South Australia covered by postcode 5153. Postcode 5153 State or territory South Australia (SA) Region Sa Subs Near 2 Add a free Biggs Flat business listing Be the first listing in Biggs Flat Common questionsWhat is the postcode for Biggs Flat?Biggs Flat, SA has the postcode 5153.What state is Biggs Flat in?Biggs Flat is in South Australia (SA).Does postcode 5153 cover more than one suburb?Yes. Postcode 5153 covers 13 localities, so the postcode alone does not identify Biggs Flat. Browse other postcodes in South Australia, or widen the search to every Australian postcode.