Home Postcode finder SA Thornlea Thornlea postcode SA Thornlea is a locality in South Australia covered by postcode 5280. Postcode 5280 State or territory South Australia (SA) Region SA Outer Suburbs Add a free Thornlea business listing Be the first listing in Thornlea Common questionsWhat is the postcode for Thornlea?Thornlea, SA has the postcode 5280.What state is Thornlea in?Thornlea is in South Australia (SA).Does postcode 5280 cover more than one suburb?Yes. Postcode 5280 covers 16 localities, so the postcode alone does not identify Thornlea. Browse other postcodes in South Australia, or widen the search to every Australian postcode.