There are not many things that feel more luxurious than climbing into a big comfy bed with a thick, plush mattress. The standard thickness for a mattress is between 6 to 9 inches – while some of the more luxurious mattresses are 12 inches. There are even some mattresses that are an astonishing 16 to 18 inches. But, how much mattress thickness do you really need? Hint: for most people it is nowhere near 16 inches.