Home Postcodes by state WA 6639 Postcode 6639 6639 is the postcode for Sandstone, WA. Localities with postcode 6639SandstoneWA Postcode 6639 State or territory Western Australia (WA) Localities 1 Council area Sandstone Council area based on Australian Bureau of Statistics data (ASGS Edition 3), CC BY 4.0. Postcode 6638 · Postcode 6640