LDL Cholesterol Calculator (Friedewald Equation)
Calculate your LDL (bad) cholesterol using the Friedewald equation from a standard lipid panel.
Understand your cardiovascular risk from cholesterol numbers.
What Is LDL Cholesterol?
Cholesterol is carried through your bloodstream attached to proteins called lipoproteins. The main types are:
- LDL (Low-Density Lipoprotein) — “bad” cholesterol. Deposits cholesterol in artery walls, forming plaques that narrow arteries and raise heart attack and stroke risk.
- HDL (High-Density Lipoprotein) — “good” cholesterol. Carries cholesterol away from arteries back to the liver.
- VLDL (Very Low-Density Lipoprotein) — carries triglycerides; roughly VLDL = Triglycerides / 5 in mg/dL.
- Triglycerides — a type of fat (lipid) in your blood; elevated levels raise cardiovascular risk.
The Friedewald Equation
Developed by William Friedewald in 1972, this formula estimates LDL from the other lipid panel values:
LDL (mg/dL) = Total Cholesterol - HDL - (Triglycerides / 5)
LDL (mmol/L) = Total Cholesterol - HDL - (Triglycerides / 2.17)
Important limitation: This formula is only valid when triglycerides are below 400 mg/dL (4.52 mmol/L). At higher TG levels, direct LDL measurement (ultracentrifugation or the Martin-Hopkins equation) should be used instead.
LDL Classification (AHA/ACC Guidelines)
| LDL Level | Category |
|---|---|
| Below 70 mg/dL | Optimal (for very high-risk patients) |
| Below 100 mg/dL | Optimal |
| 100–129 mg/dL | Near optimal |
| 130–159 mg/dL | Borderline high |
| 160–189 mg/dL | High |
| 190+ mg/dL | Very high |
Lifestyle Factors That Affect LDL
Saturated and trans fats raise LDL. Soluble fiber (oats, beans, lentils) lowers LDL by binding cholesterol in the gut. Regular aerobic exercise raises HDL. Statins (prescription medications) are the most powerful LDL-lowering drugs available, often reducing LDL by 30–50%.
This calculator is for educational purposes only. Always discuss lipid results with your healthcare provider.