LDL Calculator
Estimate LDL cholesterol from total cholesterol, HDL, and triglycerides using the Friedewald equation with interpretation.
What Is LDL Cholesterol?
Low-density lipoprotein (LDL) cholesterol is often called "bad" cholesterol because elevated levels contribute to atherosclerosis and coronary heart disease. When direct LDL is not measured, the Friedewald equation estimates LDL from total cholesterol, HDL, and triglycerides on a fasting lipid panel. See also the Cholesterol Ratio Calculator.
How LDL Is Calculated
The Friedewald formula is: LDL = total cholesterol − HDL − 0.2 × triglycerides, with all values in mg/dL. The factor 0.2 assumes triglycerides are predominantly carried in very-low-density lipoprotein (VLDL). This estimate requires a fasting sample and is most reliable when triglycerides are between 100 and 400 mg/dL.
Interpreting LDL Results
Target LDL depends on cardiovascular risk. For low-risk patients, LDL below 115 mg/dL is a common goal. Moderate-risk patients often target below 100 mg/dL, while those at high coronary risk — such as established heart disease or diabetes — may aim for below 70 mg/dL. Always interpret LDL alongside overall lipid profile, blood pressure, and clinical history.
Frequently Asked Questions
What is a normal LDL cholesterol level?
Optimal LDL is generally below 100 mg/dL for most adults. Lower targets apply for patients with diabetes, prior heart attack, or other high-risk conditions.
When is the Friedewald equation inaccurate?
Friedewald LDL is unreliable when triglycerides exceed 400 mg/dL or fall below 100 mg/dL, and in non-fasting samples. Direct LDL measurement or alternative equations should be used in those cases.
What LDL target applies to high coronary risk?
Patients with established cardiovascular disease or very high risk often target LDL below 70 mg/dL, sometimes with statin therapy and lifestyle modification per guideline recommendations.
Do I need to fast before a lipid panel?
Fasting 9–12 hours is traditionally recommended for triglyceride measurement used in Friedewald LDL. Some guidelines accept non-fasting samples when triglycerides are not markedly elevated.
How does LDL differ from total cholesterol?
Total cholesterol includes LDL, HDL, and VLDL cholesterol. LDL is the primary atherogenic fraction, so it is often the main focus for treatment decisions even when total cholesterol is within range.
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