LDL Cholesterol Calculator

Estimates LDL-C using the Friedewald equation from a standard lipid panel. Tap the unit badge on any field to switch mg/dL ⇆ mmol/L — your entered value converts automatically.

Enter lipid panel values

Total Cholesterol

HDL Cholesterol

Triglycerides

Friedewald equation is unreliable when triglycerides exceed 400 mg/dL (4.5 mmol/L). Consider direct LDL measurement.

Calculated LDL-C

– mg/dL

–

Optimal Near Border. High V.High

Friedewald equation is a validated estimate, not a direct measurement. Not valid for triglycerides > 400 mg/dL, chylomicronemia, or type III dysbetalipoproteinemia.

Other calculated lipid parameters

VLDL Cholesterol

–

Triglycerides ÷ 5

Non-HDL Cholesterol

–

Total Cholesterol − HDL

TC / HDL Ratio

–

Cardiac risk ratio

LDL / HDL Ratio

–

Atherogenic ratio

TG / HDL Ratio

–

Insulin resistance marker

Formula

LDL-C = Total Cholesterol − HDL − (Triglycerides ÷ 5) LDL-C (mmol/L) = Total Cholesterol − HDL − (Triglycerides ÷ 2.2)

About the Friedewald Equation

Developed by Friedewald, Levy, and Fredrickson in 1972, this equation estimates LDL cholesterol from a standard fasting lipid panel without needing ultracentrifugation. It remains the most widely used method for LDL-C reporting in routine clinical laboratories.

When it should not be used

Triglycerides above 400 mg/dL (4.5 mmol/L) — the estimate becomes unreliable
Non-fasting samples, where triglycerides may be transiently elevated
Type III hyperlipoproteinemia (dysbetalipoproteinemia)
Presence of chylomicrons
In these cases, direct LDL measurement or the Martin-Hopkins / Sampson equations are preferred

Other calculated parameters

VLDL Cholesterol — estimated as Triglycerides ÷ 5 (mg/dL) or ÷ 2.2 (mmol/L); reflects triglyceride-rich lipoproteins
Non-HDL Cholesterol — Total Cholesterol minus HDL; captures all atherogenic particles (LDL, VLDL, IDL, Lp(a)) and remains valid even when triglycerides are too high for Friedewald LDL
TC/HDL Ratio — a widely used cardiovascular risk index; values above 5 (male) or 4.5 (female) suggest elevated risk
LDL/HDL Ratio — atherogenic index; higher values indicate greater cardiovascular risk
TG/HDL Ratio — a surrogate marker for insulin resistance and small dense LDL particles; values above 3–3.5 (mg/dL basis) are considered elevated