Home Postcodes by state SA 5213 Postcode 5213 5213 is the postcode for Middleton, SA. Localities with postcode 5213MiddletonSA Postcode 5213 State or territory South Australia (SA) Localities 1 Council area Alexandrina Council area based on Australian Bureau of Statistics data (ASGS Edition 3), CC BY 4.0. Postcode 5212 · Postcode 5214