Home Postcode finder SA Lyndhurst Lyndhurst postcode SA Lyndhurst is a locality in South Australia covered by postcode 5731. Postcode 5731 State or territory South Australia (SA) Region SA Outer Suburbs Add a free Lyndhurst business listing Be the first listing in Lyndhurst Common questionsWhat is the postcode for Lyndhurst?Lyndhurst, SA has the postcode 5731.What state is Lyndhurst in?Lyndhurst is in South Australia (SA).Does postcode 5731 cover more than one suburb?Yes. Postcode 5731 covers 9 localities, so the postcode alone does not identify Lyndhurst. Browse other postcodes in South Australia, or widen the search to every Australian postcode.