Home Postcode finder QLD St Mary St Mary postcode QLD St Mary is a locality in Queensland covered by postcode 4650. Postcode 4650 State or territory Queensland (QLD) Region Sunshine Coast Add a free St Mary business listing Be the first listing in St Mary Common questionsWhat is the postcode for St Mary?St Mary, QLD has the postcode 4650.What state is St Mary in?St Mary is in Queensland (QLD).Does postcode 4650 cover more than one suburb?Yes. Postcode 4650 covers 48 localities, so the postcode alone does not identify St Mary. Browse other postcodes in Queensland, or widen the search to every Australian postcode.