The ratio of cholesterol to HDL is determined by dividing the total cholesterol level by the HDL cholesterol level. It is used to assess the risk of cardiovascular disease because it provides a good indication of the proportion of total cholesterol that is beneficial (i.e. high-density lipoprotein HDL). Tools used to evaluate the risk of heart disease, such as QRisk, use the cholesterol/HDL ratio to determine the probability of a heart attack.