Measuring cholesterol requires an understanding of the different types of cholesterol. Your total cholesterol is the sum of your LDL (low-density lipoprotein) levels plus your HDL (high-density lipoprotein) levels. LDL is considered "bad" cholesterol, and HDL is considered "good" cholesterol. A cholesterol ratio compares the HDL to the total cholesterol measurement. Ideally, this ratio should be below 5 to 1 because either elevated LDL levels or HDL that is too low can lead to health conditions such as heart disease and stroke.
Ask your doctor to administer a cholesterol test, which is conducted using a blood sample.
Obtain the results from your doctor. You should be able to find your total cholesterol, as well as your HDL and LDL.
Divide your total cholesterol by your HDL. For instance, if your total cholesterol is 200 mg per decilitre and your HDL is 40 mg per decilitre, divide 200 by 40 to get 5.
State your answer in terms of a ratio. Because 40 divides into 200 five times, the ratio would be 5 to 1, or 5:1.