Definition of Bottom Out

Meaning of the Term as it Pertains to Mattresses

What is Bottom Out?

When a mattress lacks support due to the amount of weight resting on top, it is said to bottom out. The term typically applies to foam mattresses. The nature of foam sleeping materials allows those mattresses to be thinner than their innerspring counterparts. However, if a mattress is too thin for a sleeper's body weight, support will fail.

The point at which a foam mattress bottoms out depends on the thickness of the mattress and the weight of the person on top. For example, a six-inch foam mattress will bottom out when someone about 170 pounds or heavier rests on it. Increasing the thickness of a foam mattress allows for more weight to rest on top without bottoming out. Softness and firmness of foam also affect the amount of weight that will make a mattress bottom out.