If you do not know which size to choose, we recommend that a mattress for individual use should not be less than 98cm or 38" wide, for mattresses where there are two sleepers it should not be less than 152cm or 60" wide. Regarding the length of the mattress, it is recommended that it be about 10cm or 4" longer than the sleeper is. In the case of double beds, the tallest person will be taken as a reference.