Home Postcode finder SA Penfield Penfield postcode SA Penfield is a locality in South Australia covered by postcode 5121. Postcode 5121 State or territory South Australia (SA) Region Sa Subs Near 1 Add a free Penfield business listing Be the first listing in Penfield Common questionsWhat is the postcode for Penfield?Penfield, SA has the postcode 5121.What state is Penfield in?Penfield is in South Australia (SA).Does postcode 5121 cover more than one suburb?Yes. Postcode 5121 covers 3 localities, so the postcode alone does not identify Penfield. Browse other postcodes in South Australia, or widen the search to every Australian postcode.