Home Postcode finder NSW Mayers Flat Mayers Flat postcode NSW Mayers Flat is a locality in New South Wales covered by postcode 2423. Postcode 2423 State or territory New South Wales (NSW) Region Hunter Add a free Mayers Flat business listing Be the first listing in Mayers Flat Common questionsWhat is the postcode for Mayers Flat?Mayers Flat, NSW has the postcode 2423.What state is Mayers Flat in?Mayers Flat is in New South Wales (NSW).Does postcode 2423 cover more than one suburb?Yes. Postcode 2423 covers 20 localities, so the postcode alone does not identify Mayers Flat. Browse other postcodes in New South Wales, or widen the search to every Australian postcode.