For predicting your risk of heart disease, many doctors now believe that determining your non-HDL cholesterol level may be more useful than calculating your cholesterol ratio. And either option appears to be a better risk predictor than your total cholesterol level or even your low-density lipoprotein (LDL, or "bad") cholesterol level.
Non-HDL cholesterol, as its name implies, simply subtracts your high-density lipoprotein (HDL, or "good") cholesterol number from your total cholesterol number. So it contains all the "bad" types of cholesterol.
An optimal level of non-HDL cholesterol is less than 130 milligrams per deciliter (mg/dL), or 3.37 millimoles per liter (mmol/L). Higher numbers mean a higher risk of heart disease.
To calculate your cholesterol ratio, divide your total cholesterol number by your HDL cholesterol number. So if your total cholesterol is 200 mg/dL (5.2 mmol/L) and your HDL is 50 mg/dL (1.3 mmol/L), your ratio would be 4-to-1. Higher ratios mean a higher risk of heart disease.