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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
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
LDL-C Reference Categories (ATP III / NCEP)
- <100 mg/dL — Optimal
- 100–129 mg/dL — Near optimal / above optimal
- 130–159 mg/dL — Borderline high
- 160–189 mg/dL — High
- ≥190 mg/dL — Very high
