Home Postcode finder SA Northgate Northgate postcode SA Northgate is a locality in South Australia covered by postcode 5085. Postcode 5085 State or territory South Australia (SA) Region Sa Subs Near 1 Add a free Northgate business listing Be the first listing in Northgate Common questionsWhat is the postcode for Northgate?Northgate, SA has the postcode 5085.What state is Northgate in?Northgate is in South Australia (SA).Does postcode 5085 cover more than one suburb?Yes. Postcode 5085 covers 5 localities, so the postcode alone does not identify Northgate. Browse other postcodes in South Australia, or widen the search to every Australian postcode.