"Futon mattress" covers two very different products. The traditional Japanese shikibuton is a 2–4 inch cotton-batting pad laid on a tatami mat or the floor and folded away each morning. The Western futon is a 6–10 inch mattress that lives on a bi-fold or tri-fold wood or metal frame and converts between sofa and bed. Both are legitimate, but they suit opposite use cases, and buying the wrong one is the most common mistake in this category.
WESTERN FUTON TYPES. All-cotton is the original: firm, breathable, inexpensive, and it compresses and lumps within a couple of years under nightly use. Cotton-foam blends add a foam core between cotton layers, hold their loft longer, and are the mainstream choice. Innerspring futons put a coil unit inside and sleep closest to a conventional mattress, but they fold poorly and are heavy. Memory foam futons give the best pressure relief and the worst breathability. Latex futons are the most durable and the most expensive, easily $700–$1,200, and are the only type that reliably survives ten years of nightly use.
THICKNESS BY USE CASE. Under 6 inches: sofa-first, occasional overnight use only. 6–8 inches: the balanced range, comfortable for regular guests and folds cleanly on a bi-fold frame. 8–10 inches: primary-bed territory, genuinely sleepable every night, but stiff to fold and hard on the frame hardware. Above 10 inches you are buying a mattress that happens to be sold as a futon and it will not fold on most frames.
SIZES. Futon mattresses follow standard bed widths but frame compatibility varies. Twin 39" × 75", full 54" × 75" (the most common futon size by a wide margin), queen 60" × 80". Chair and loveseat futons run 28" × 54" and 54" × 54". Bi-fold frames fold along the width, so a full futon becomes a 54"-wide sofa; tri-fold frames fold twice and take thinner mattresses. Confirm your frame's fold style before ordering, because a thick mattress on a tri-fold frame will not close.
TRADITIONAL SHIKIBUTON. If you are floor sleeping, this is the correct product and a Western futon is not. A shikibuton is 2–4 inches of layered cotton batting, weighs 15–25 lbs, and is designed to be folded and aired daily — that daily airing is not optional, because floor sleeping traps body moisture against the underside and the pad will mildew without it. Pair with a tatami mat or a slatted platform for airflow. Firmness is very high; most Western sleepers need two to three weeks to adapt, and side sleepers often need a 2-inch wool topper on top.
FIRMNESS EXPECTATIONS. Futons in general sleep firmer than any conventional mattress. Cotton compresses under body heat and weight, so the surface you feel after 30 minutes is firmer than the one you lay down on. Back and stomach sleepers usually get along with them immediately. Side sleepers should choose a cotton-foam or latex futon at 8 inches minimum, or plan on a topper.
MAINTENANCE IS WHAT DETERMINES LIFESPAN. Cotton futons must be rotated and flipped monthly and aired in sunlight every few months to drive out moisture and restore loft — this is the difference between a two-year and a five-year mattress. Never leave a cotton futon folded on a frame continuously for months; the fold line will compress permanently. Vacuum the surface when you rotate it, since cotton batting sheds and attracts dust mites more readily than foam.
AIRFLOW AND MOLD. Futon frames with tight slats or solid decks trap moisture in the same way RV platforms do. Aim for slats no more than 3 inches apart with gaps, and if the futon lives on the floor, lift it daily. Mold on the underside is the most common way a futon dies before its material actually wears out.
WHAT THEY COST. All-cotton full: $120–$250. Cotton-foam blend full: $200–$400. Innerspring full: $250–$450. Memory foam full: $300–$500. Latex full: $700–$1,200. Traditional shikibuton: $200–$500 depending on cotton grade and thickness. Frames add $150–$500.
SHOULD YOU BUY ONE. A futon is the right purchase for a small apartment, a dual-purpose office and guest room, a dorm, or a deliberate floor-sleeping setup. It is the wrong purchase as a primary bed for a side sleeper, for anyone over about 230 lbs (cotton compresses too fast to be supportive at that weight), or for anyone unwilling to rotate and air it on schedule. For a guest room where the sofa function matters more than the sleep function, a futon still beats a sleeper sofa on comfort per dollar because it has no fold mechanism and no support bar.