Friedewald LDL Cholesterol Calculator

Calculate LDL cholesterol using the Friedewald formula. Valid when triglycerides ≤ 400 mg/dL.

For educational and clinical reference. Not a substitute for medical judgment. See the medical disclaimer.
LDL Cholesterol
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References

  1. Friedewald WT, Levy RI, Fredrickson DS. Estimation of the concentration of low-density lipoprotein cholesterol in plasma, without use of the preparative ultracentrifuge. Clin Chem. 1972;18(6):499-502.

How to use

  1. Enter total cholesterol, HDL, and triglycerides (all mg/dL).
  2. LDL updates instantly.
  3. If TG > 400, use a different method (Martin/Hopkins or direct LDL).

Frequently asked questions

What is the Friedewald formula?

LDL (mg/dL) = Total Cholesterol − HDL − Triglycerides / 5. Valid when triglycerides ≤ 400 mg/dL.

When is Friedewald invalid?

When triglycerides exceed 400 mg/dL, or in chylomicronemia or type III hyperlipoproteinemia. In those cases, direct LDL measurement or the Martin/Hopkins or Sampson equations are preferred.

Why divide triglycerides by 5?

Friedewald assumed that VLDL cholesterol ≈ triglycerides / 5 (mg/dL), based on observed VLDL composition in fasting samples. This relationship breaks down at high triglyceride levels.

Should the patient be fasting?

Friedewald was derived from fasting samples. Non-fasting samples may underestimate LDL by ~10%.

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