Home Postcodes by state NSW 2154 Postcode 2154 2154 is the postcode for Castle Hill, NSW. Localities with postcode 2154Castle HillNSW Postcode 2154 State or territory New South Wales (NSW) Localities 1 Council area Mainly The Hills, partly Hornsby Council area based on Australian Bureau of Statistics data (ASGS Edition 3), CC BY 4.0. Postcode 2153 · Postcode 2155