In metric land we simply state the size of the mattress. I've got a 160cm wide and 220cm long bed, for example.

Length is typically 200cm, but sometimes I encounter 190cm beds in hotels (which are too short for me, as I'm 1,92m tall). 220cm beds are extra long (and mine was 200x220 before I cut the aluminum profiles to reduce it to 160x220 after I divorced)

Note how we also measure humans in meters and beds in centimeters, but it's just a matter of a decimal point/comma.