Looking for a mattress fit for a king? Our range of king size beds and mattresses is for you! We have a stunning variety of the best king size beds that can either be sold as a stand alone king size mattress or as an ensemble with a king size bed base and mattress. The king mattress size is the largest standard mattress size available - the standard size of a king bed mattress is 1,830 mm x 2,040 mm. Use our handy Mattress Selector to find the perfect king size bed and mattress to suit your comfort preference, health needs and price range.