Home Postcode finder QLD Gladstone Harbour Gladstone Harbour postcode QLD Gladstone Harbour is a locality in Queensland covered by postcode 4680. Postcode 4680 State or territory Queensland (QLD) Region Central QLD Add a free Gladstone Harbour business listing Be the first listing in Gladstone Harbour Common questionsWhat is the postcode for Gladstone Harbour?Gladstone Harbour, QLD has the postcode 4680.What state is Gladstone Harbour in?Gladstone Harbour is in Queensland (QLD).Does postcode 4680 cover more than one suburb?Yes. Postcode 4680 covers 41 localities, so the postcode alone does not identify Gladstone Harbour. Browse other postcodes in Queensland, or widen the search to every Australian postcode.