Home Postcode finder WA Cowalla Cowalla postcode WA Cowalla is a locality in Western Australia covered by postcode 6503. Postcode 6503 State or territory Western Australia (WA) Region Wa Subs 4 Coast Add a free Cowalla business listing Be the first listing in Cowalla Common questionsWhat is the postcode for Cowalla?Cowalla, WA has the postcode 6503.What state is Cowalla in?Cowalla is in Western Australia (WA).Does postcode 6503 cover more than one suburb?Yes. Postcode 6503 covers 20 localities, so the postcode alone does not identify Cowalla. Browse other postcodes in Western Australia, or widen the search to every Australian postcode.