To calculate your cholesterol ratio, divide your high-density lipoprotein (HDL, or good) cholesterol number into your total cholesterol number. An optimal ratio is less than 3.5-to-1. A higher ratio means a higher risk of heart disease. Non-HDL cholesterol, as its name implies, simply subtracts your HDL cholesterol number from your total cholesterol number. So it contains all the bad types of cholesterol.