Friedewald LDL Cholesterol Calculator
The Friedewald equation estimates LDL cholesterol from a standard lipid panel: LDL = total cholesterol − HDL − (triglycerides ÷ 5) in mg/dL, or − (triglycerides ÷ 2.2) in mmol/L. It is unreliable when triglycerides are high (originally above 400 mg/dL) or in non-fasting samples.
Quick answer
The Friedewald equation estimates LDL cholesterol from a fasting lipid panel: in mg/dL, LDL = total cholesterol − HDL − (triglycerides ÷ 5); in mmol/L, divide triglycerides by 2.2 instead. The estimate becomes unreliable when triglycerides are high (above 400 mg/dL, about 4.5 mmol/L) or the sample is non-fasting.
Lipid panel
Use a fasting lipid panel. The estimate is unreliable when triglycerides exceed 400 mg/dL.
How to use the Friedewald LDL calculator
- 1Choose units and enter the panel. Select mg/dL or mmol/L, then enter total cholesterol, HDL cholesterol and triglycerides from a fasting lipid panel.
- 2Read the calculated LDL. The tool subtracts HDL and triglycerides ÷ 5 (or ÷ 2.2 for mmol/L) from total cholesterol and shows the estimated LDL.
- 3Check the reliability flag. If triglycerides exceed the validity limit, the tool flags the estimate as unreliable — a direct (measured) LDL is then preferred. A clinician interprets the result.
Medical disclaimer: This is general health information, not medical advice. It does not diagnose or treat any condition, and the results are estimates based on public reference formulas. Always consult a qualified doctor about your individual health. If you think you may have a medical emergency, contact your local emergency services immediately.
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Book a consultationFrequently asked questions
When is the Friedewald LDL estimate unreliable?⌄
The equation is invalid when triglycerides exceed 400 mg/dL (about 4.5 mmol/L), because the triglycerides ÷ 5 term no longer approximates VLDL cholesterol. It is also unreliable in non-fasting samples and in type III dyslipidaemia. A directly measured LDL is preferred in those cases.
Why divide triglycerides by 5 (or 2.2)?⌄
The triglycerides ÷ 5 term (mg/dL) estimates the cholesterol carried in VLDL particles. In mmol/L the equivalent divisor is 2.2. This approximation only holds within the validated triglyceride range.
Does Friedewald LDL replace a measured LDL?⌄
No. It is a convenient estimate from a standard panel, but a directly measured LDL is more accurate, especially at high triglycerides or low LDL values. A clinician decides which to use.
Is my data stored?⌄
No. The calculator runs entirely in your browser; nothing you enter is sent to a server.
Sources & validation
This calculator reproduces the published Friedewald LDL score, validated for estimating LDL cholesterol from a fasting lipid panel.
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