A mattress is the general thick, cushioned pad you sleep on, usually resting on a bed frame. A futon is a specific, thinner type of padded mattress that can be laid straight on the floor or set on a folding frame that converts between a bed and a sofa. If it needs to fold flat for daytime seating, it is a futon rather than a standard mattress.
The core difference
Mattress is the general sleeping pad, while futon is a thinner, foldable version designed to double as floor bedding or a sofa.
- mattress — a thick, cushioned pad, usually on a bed frame, that a person lies on to sleep: They bought a new mattress after years of sleeping on a lumpy old one.
- futon — a thin, padded cotton mattress laid on the floor or set on a folding frame that converts between a bed and a sofa: We keep a futon in the spare room for guests.
How to tell them apart
Thickness and flexibility are the giveaways. A standard mattress is thick and made to stay on a bed frame; it is not designed to fold up or double as seating. A futon is thinner and padded so it can be rolled or folded flat, whether that means laying it directly on the floor or fitting it to a frame that switches between bed and sofa.
The mix-up mostly comes up in furniture shopping, where futon is sometimes used loosely for any low, minimal-frame bed. If the piece is meant to fold away into a sofa for daytime use, futon is the accurate term; if it simply sits on a permanent bed frame, mattress covers it.
