Home Postcode finder WA Chadwick Chadwick postcode WA Chadwick is a locality in Western Australia covered by postcode 6450. Postcode 6450 State or territory Western Australia (WA) Region Wa Subs 1 G Flds Add a free Chadwick business listing Be the first listing in Chadwick Common questionsWhat is the postcode for Chadwick?Chadwick, WA has the postcode 6450.What state is Chadwick in?Chadwick is in Western Australia (WA).Does postcode 6450 cover more than one suburb?Yes. Postcode 6450 covers 23 localities, so the postcode alone does not identify Chadwick. Browse other postcodes in Western Australia, or widen the search to every Australian postcode.