Home Postcodes by state WA 6176 Postcode 6176 6176 is the postcode for Karnup, WA. Localities with postcode 6176KarnupWA Postcode 6176 State or territory Western Australia (WA) Localities 1 Council area Rockingham Council area based on Australian Bureau of Statistics data (ASGS Edition 3), CC BY 4.0. Postcode 6175 · Postcode 6180