Cholesterol is a waxy, fat-like substance that’s found in all the cells in your body. Your body needs some cholesterol to make hormones, vitamin D, and substances that help you digest foods.
Working out a person’s cholesterol ratio is important because it can help a doctor determine a person’s risk of heart disease.
Formula to calculate total cholesterol.

HDL cholesterol stands for high-density lipoprotein and is often called “good” cholesterol. Over 60 mg/dL is generally a desirable amount for your HDL levels.
LDL cholesterol stands for low-density lipoprotein and is considered “bad” cholesterol. Under 100 milligrams per deciliter (mg/dL) is what you should aim for.
Triglycerides are the way your body transports fat in the blood. A desirable number is below 150 mg/dL.
Example:
Suppose your HDL level is 70 mg/dL and your LDL level is 80 mg/dL, calculate your total cholesterol if your triglycerides are 100 mg/dL.

Therefore, your total cholesterol is 170 mg/dL.