LDL cholesterol calculator

Methodology

How this is calculated

LDL cholesterol is total cholesterol minus HDL cholesterol minus one fifth of the triglycerides, all in mg/dL: LDL = TC - HDL - TG / 5. The page uses the 1972 equation as published in mg/dL and converts your units around it: a mmol/L entry is converted to mg/dL (cholesterol at 38.67 mg/dL per mmol/L, triglycerides at 88.57), the equation runs once, and the answer is converted back. So switching units never changes the estimate. Results show whole mg/dL or two-decimal mmol/L. Non-HDL cholesterol is total cholesterol minus HDL cholesterol.

Where the data comes from

Friedewald WT, Levy RI, Fredrickson DS, Estimation of the concentration of low-density lipoprotein cholesterol in plasma, without use of the preparative ultracentrifuge, Clinical Chemistry 1972;18(6):499-502. The paper names three limits on the method. The one this page enforces is its third: LDL cholesterol “cannot always be accurately estimated when the plasma triglyceride concentration exceeds 400 mg/100 ml” (mg/100 ml is mg/dL), and the paper's own comparison left out samples at 400 and above. The unit conversions are the standard molar-mass factors, not numbers from the paper.

Last updated

September 23, 2026

What this does not account for

Whether the sample was taken fasting, which the paper's method assumes, the paper's other two limits (samples containing chylomicrons, and a rare inherited lipid disorder it names as Type III), and every other fact a clinician weighs. A lab that reports a measured or differently calculated LDL may print a number that does not match this one.