Most common
Twin
A useful starting point for kids' rooms, bunk-compatible setups, daybeds, and tighter spaces. Confirm frame and room dimensions first.
Kids' rooms, dorms & first apartments
A practical bed for the room they're growing into.
Start with dependable support for a growing child. Then account for the room, the frame, and whether the mattress may move to a dorm or first apartment later.
Dorm standard
Twin XL
Five inches longer than a standard Twin and common in college housing. Always check the school's exact requirements before buying.
Longer-term flexibility
Full
More room for a teen or young adult when floor space allows, with broader usefulness in a future guest room or first apartment.
Choose for the sleeper, not only the size.
Look for a comfortable feel, appropriate support, a breathable protector, and a foundation that works with the mattress. For dorms, verify size, allowable height, delivery rules, and what furniture is already provided.