Home Postcode finder NSW Williamtown Williamtown postcode NSW Williamtown is a locality in New South Wales covered by postcode 2318. Postcode 2318 State or territory New South Wales (NSW) Region Hunter Add a free Williamtown business listing Be the first listing in Williamtown Common questionsWhat is the postcode for Williamtown?Williamtown, NSW has the postcode 2318.What state is Williamtown in?Williamtown is in New South Wales (NSW).Does postcode 2318 cover more than one suburb?Yes. Postcode 2318 covers 7 localities, so the postcode alone does not identify Williamtown. Browse other postcodes in New South Wales, or widen the search to every Australian postcode.