This is the worst bed ever! There is no right number all the numbers suck, they are either to hard, like sleeping on a floor, or so soft you sink into a big hammock, either way you always wake up with MUCH soreness. I've had this bed for over a year now and I'm dying to get rid of it, but hubby is sick of sending money on mattresses. This bed is just a big gimmick to me, I don't think there is any real science to back up any of there claims.