Enough space to sleep in is hugely important to the quality of your rest. A king mattress is the most popular size in the UK. We have a limited selection of standard king size mattresses which measure 150cm x 200cm available at great prices. This is the nearest equivalent to what used to be known as the traditional 5ft size. Scroll to the foot of this page for more tips to help you pick the right option. Even mattresses featured here in Special Offers are included in our 100 night trial.