Home Postcodes by state WA 6446 Postcode 6446 6446 is the postcode for Grass Patch, WA. Localities with postcode 6446Grass PatchWA Postcode 6446 State or territory Western Australia (WA) Localities 1 Council area Esperance Council area based on Australian Bureau of Statistics data (ASGS Edition 3), CC BY 4.0. Postcode 6445 · Postcode 6447