Home Postcode finder SA Gladstone Gladstone postcode SA Gladstone is a locality in South Australia covered by postcode 5473. Postcode 5473 State or territory South Australia (SA) Region SA Outer Suburbs Add a free Gladstone business listing More business listings in Gladstone Businesses in GladstoneGladstone High SchoolMain North Rd · 08 86622171Gladstone Primary School2 West Terrace · 08 86622235St Joseph's Parish School1 West Terrace · 08 86622016 Common questionsWhat is the postcode for Gladstone?Gladstone, SA has the postcode 5473.What state is Gladstone in?Gladstone is in South Australia (SA).Does postcode 5473 cover more than one suburb?No. Postcode 5473 covers Gladstone only, which is unusual - most Australian postcodes cover several localities. Browse other postcodes in South Australia, or widen the search to every Australian postcode.