What are double mattress dimensions? The Australian standard dimensions of a double mattress are 137 cm x 188 cm. The double bed is perfect if you want to downsize from a queen or have a growing teenager. With a slightly smaller footprint than a queen mattress the double may give you that extra space you need in the bedroom whilst still being comfortable for two people. The double All our mattresses are Australian made and we only use environmentally friendly ingredients: GECA approved foams and natural fabrics. Plus, all of our mattresses are covered by a 10-year guarantee, so you can be sure you’re investing in a quality mattress that will stand the test of time. So, if you’re looking for your perfect double size mattress visit our Sydney showroom in Rozelle.