LDL Formula Calculator (Friedewald Equation)
Use your lipid panel values to estimate LDL cholesterol. Enter values exactly as reported by your lab.
LDL = Total Cholesterol - HDL - (Triglycerides / 2.2) (mmol/L)
Tip: Friedewald-based LDL can be unreliable when triglycerides are high. See notes below.
What is a formula LDL calculator?
A formula LDL calculator estimates low-density lipoprotein cholesterol (LDL-C) using common lipid panel measurements: total cholesterol, HDL cholesterol, and triglycerides. It is widely used because most routine blood tests include these values, and the estimate is fast and inexpensive.
The most common method is the Friedewald formula. While practical, it is still an estimate, not a direct LDL measurement.
How the LDL formula works
Friedewald equation
- mg/dL: LDL = TC - HDL - (TG / 5)
- mmol/L: LDL = TC - HDL - (TG / 2.2)
In this equation, TG/5 (or TG/2.2) approximates very-low-density lipoprotein cholesterol (VLDL-C). Subtracting HDL and estimated VLDL from total cholesterol gives an estimated LDL value.
Why this matters clinically
LDL cholesterol is a major cardiovascular risk marker and treatment target in many guidelines. A reliable estimate helps clinicians decide whether lifestyle changes alone are appropriate or whether medications should be discussed.
Interpreting your LDL result
General adult reference ranges (mg/dL):
| LDL Level (mg/dL) | Common Interpretation |
|---|---|
| < 100 | Optimal |
| 100–129 | Near optimal |
| 130–159 | Borderline high |
| 160–189 | High |
| ≥ 190 | Very high |
Risk context matters: diabetes, hypertension, smoking status, age, family history, and known cardiovascular disease all influence your LDL target.
Limitations of calculated LDL
When accuracy drops
- Triglycerides above about 400 mg/dL (about 4.5 mmol/L)
- Non-fasting samples (in certain cases)
- Unusual lipid disorders or severe metabolic disease
If any of these apply, your clinician may order a direct LDL test or a different particle-based test for better precision.
How to improve LDL cholesterol
- Prioritize high-fiber foods (oats, legumes, vegetables, fruit)
- Reduce trans fats and limit saturated fats
- Increase physical activity (most days of the week)
- Maintain a healthy body weight and waist circumference
- Stop smoking and moderate alcohol intake
- Take prescribed medications consistently if recommended
Frequently asked questions
Is calculated LDL the same as direct LDL?
No. Calculated LDL is estimated from other values. Direct LDL is measured by lab assay.
Can LDL be “too low”?
Very low LDL may be intentional for high-risk patients. Your treatment target should be individualized by your clinician.
Should I use this calculator for diagnosis?
Use it for education and tracking, not diagnosis. Medical decisions should be based on full clinical evaluation.