Home Postcode finder WA Whitby Whitby postcode WA Whitby is a locality in Western Australia covered by postcode 6123. Postcode 6123 State or territory Western Australia (WA) Region North West Suburbs Add a free Whitby business listing Be the first listing in Whitby Common questionsWhat is the postcode for Whitby?Whitby, WA has the postcode 6123.What state is Whitby in?Whitby is in Western Australia (WA).Does postcode 6123 cover more than one suburb?Yes. Postcode 6123 covers 2 localities, so the postcode alone does not identify Whitby. Browse other postcodes in Western Australia, or widen the search to every Australian postcode.