What are the dimensions of a single & king single mattress? The standard dimension of an Australian single mattress are 92 cm x 188 cm, the smallest of mattresses and the dimensions of a king single mattress are 107 cm x 203 cm. The single mattress is the same length of a double mattress while the king single is the same length of a queen and king mattress. Both sizes can be ideal for kids, a spare room or anyone looking to downsize. 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 queen size mattress visit our Sydney showroom in Rozelle.