Home Postcode finder WA Koojan Koojan postcode WA Koojan is a locality in Western Australia covered by postcode 6510. Postcode 6510 State or territory Western Australia (WA) Region Wa Subs 4 Coast Add a free Koojan business listing Be the first listing in Koojan Common questionsWhat is the postcode for Koojan?Koojan, WA has the postcode 6510.What state is Koojan in?Koojan is in Western Australia (WA).Does postcode 6510 cover more than one suburb?Yes. Postcode 6510 covers 6 localities, so the postcode alone does not identify Koojan. Browse other postcodes in Western Australia, or widen the search to every Australian postcode.