With the width of a single bed, but length of a king, a single long mattress is perfect for those pre-teen growth spurts. Not only that but a long single mattress and bed base are the best solution for guest rooms with limited space. We have a stunning variety of single long mattresses for purchase either as a mattress or an ensemble with a long single bed base. The standard size of a single long mattress is 920 x 2,040 mm. Use our handy Mattress Selector to find the perfect single long mattress and bed base for you and your needs.