Futon mattress sizes can range from twin to California King, with measurements from 39 inches by 75 inches to 72 inches by 84 inches. Mattress thickness can vary from 4 to over 12 inches.
Most futon couches have full- or queen-size mattresses measuring 54 inches by 75 inches or 60 inches by 80 inches. However, companies also offer king-size mattresses, which measure 76 inches by 80 inches or 72 inches by 84 inches. Love seats are also available with full- or twin-size options measuring 54 inches by 75 inches or 39 inches by 75 inches.
Mattresses can also vary in thickness, ranging from 4 to 12 inches depending on how many layers of support a person wants.
Chair futon mattresses are typically 28 inches by 54 inches in size.