Choosing between a King and Queen size mattress can be a tough decision (size, pricing, etc). We’ve made it easy to choose the best one with our guide. Dimensions. Both full beds and twin beds are 75 inches (191 cm) long. They differ when it comes to width, however. At 54 inches (137 cm) wide, a full size bed is nearly as wide as a queen size bed.Twin beds are much narrower, measuring a mere 39 inches (99 cm) across. Buy Bedsure Mattress Pad Queen Size Hypoallergenic – Antibacterial, Breathable – Ultra Soft Quilted Mattress Protector, Fitted Sheet Mattress Cover White: Mattress Pads – Amazon.com FREE DELIVERY possible on eligible purchases The Signature Sleep Memoir 12 inch mattress is made with a 4″ top layer of comfortable Memoir Foam, followed by 8 inches of high density foam; this allows for the mattress to mold to the body’s natural shape for a comfortable night’s sleep Invest in comfortable, restful sleep for your family with mattresses that suit individual sleeping styles and preferred levels of firmness. Overstock.com – Your Online Bedroom Furniture Store! Get 5% in rewards with Club O! – Full Size Mattresses The bed sizes available in the United States are the twin, single, double, full, queen, king, California king, Western King, and Eastern King. How in the world is anyone supposed to know the difference between all the bed sizes on the market today? Even the sales person in your local department .