Home Postcode finder SA Square Mile Square Mile postcode SA Square Mile is a locality in South Australia covered by postcode 5291. Postcode 5291 State or territory South Australia (SA) Region SA Outer Suburbs Add a free Square Mile business listing Be the first listing in Square Mile Common questionsWhat is the postcode for Square Mile?Square Mile, SA has the postcode 5291.What state is Square Mile in?Square Mile is in South Australia (SA).Does postcode 5291 cover more than one suburb?Yes. Postcode 5291 covers 34 localities, so the postcode alone does not identify Square Mile. Browse other postcodes in South Australia, or widen the search to every Australian postcode.