About this calculator
This calculator estimates LDL cholesterol from total cholesterol, HDL cholesterol, and triglycerides using the classic Friedewald equation. It supports both mg/dL and mmol/L.
The Friedewald estimate has important limitations, especially when triglycerides are high, LDL is very low, or a direct LDL/non-HDL/ApoB strategy is preferred clinically. Use your clinician’s interpretation for treatment decisions.
Uses the Friedewald LDL-C estimate: LDL-C = total cholesterol − HDL-C − triglycerides/5 in mg/dL, or LDL-C = total cholesterol − HDL-C − triglycerides/2.2 in mmol/L. It should not be used when triglycerides are very high, classically ≥400 mg/dL (about 4.5 mmol/L).
Activated — Friedewald LDL estimate
The Friedewald equation is not reliable when triglycerides are very high, commonly at or above 400 mg/dL, and may be less accurate in some nonfasting or dyslipidemia contexts.
Formula and method
For mg/dL: LDL-C = total cholesterol − HDL-C − triglycerides ÷ 5. For mmol/L: LDL-C = total cholesterol − HDL-C − triglycerides ÷ 2.2. The calculator warns when triglycerides are at or above the classic unreliability threshold.
Limitations and when not to rely on this result
- The Friedewald equation is not reliable when triglycerides are very high, commonly at or above 400 mg/dL, and may be less accurate in some nonfasting or dyslipidemia contexts.
- Use the units shown on the page and confirm unusual lipid results with a clinician or laboratory report.
- Treatment decisions depend on overall cardiovascular risk, guidelines, and clinician judgment.
Frequently asked questions
What is the Friedewald equation? +
It estimates LDL cholesterol by subtracting HDL cholesterol and estimated VLDL cholesterol from total cholesterol.
When should Friedewald LDL not be used? +
It is classically considered unreliable when triglycerides are 400 mg/dL or higher, about 4.5 mmol/L, and may be less accurate in other high-triglyceride or very-low-LDL settings.
Can I use non-fasting triglycerides? +
Some lipid panels are accepted non-fasting, but high non-fasting triglycerides can reduce the reliability of calculated LDL. Follow your clinician or lab instructions.
Is calculated LDL the same as directly measured LDL? +
No. It is an estimate. Some clinical situations may call for direct LDL, non-HDL cholesterol, ApoB, or another calculation method.
Can this determine whether I need a statin? +
No. Medication decisions depend on overall cardiovascular risk, diabetes, kidney disease, age, blood pressure, smoking, prior events, and clinician judgment.