Home Postcodes by state WA 6021 Postcode 6021 6021 is the postcode for 2 localities in WA: Balcatta and Stirling. Localities with postcode 6021BalcattaWAStirlingWA Postcode 6021 State or territory Western Australia (WA) Localities 2 Council area Stirling Council area based on Australian Bureau of Statistics data (ASGS Edition 3), CC BY 4.0. Postcode 6020 · Postcode 6022