LDL Cholesterol Calculator

Evidence‑based cardiovascular risk assessment tool. Compute LDL-C, non‑HDL cholesterol, TC/HDL ratio, and guideline‑aligned risk category using your lipid panel.

mg/dL
Standard unit: mg/dL (US). For mmol/L multiply by 38.67.
mg/dL
mg/dL
Fasting sample preferred for accuracy.
Friedewald: LDL = TC - HDL - (TG/5). Valid for TG ≤ 400 mg/dL.
Quick examples:
Healthy profile
Elevated LDL
High TG
Optimal lipids
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Clinical Significance of LDL Cholesterol & Guideline-Based Interpretation

Low‑density lipoprotein (LDL) cholesterol is often called "bad cholesterol" because elevated levels promote atherosclerotic plaque formation, increasing risk for coronary artery disease, stroke, and peripheral artery disease. According to the 2018 ACC/AHA Blood Cholesterol Guideline, LDL reduction is a primary target for primary and secondary prevention. This calculator implements two validated estimation methods:

• Friedewald equation (1972): LDL = TC − HDL − (TG / 5). Valid when TG < 400 mg/dL, assumes constant VLDL cholesterol ratio.
• Martin-Hopkins equation (2013): Uses a programmable factor based on TG and non‑HDL levels, improves accuracy in hypertriglyceridemic and diabetic patients (NIH supported). Simplified version in this tool

Why LDL Matters

Each 1 mmol/L (≈38.7 mg/dL) reduction in LDL is associated with ~22% decrease in major cardiovascular events (CTT meta‑analysis). The calculator displays risk category aligned with ESC/EAS 2019 and ACC/AHA thresholds: Optimal (<70 mg/dL for high‑risk patients), Near Optimal (70–99), Borderline High (100–129), High (130–159), and Very High (≥160). Non‑HDL cholesterol (TC minus HDL) is a secondary predictor, with recommended target <100 mg/dL for high‑risk individuals.

Formula Accuracy & Limitations

Friedewald underestimates LDL when TG > 400 mg/dL; in such cases direct LDL measurement is advised. The Martin-Hopkins equation (full version) offers better precision for TG levels up to 800 mg/dL. However, this tool uses a simplified, TG‑range‑based factor that is not clinically validated. It is intended for educational illustration only. Always confirm abnormal results with a direct LDL‑C test or laboratory measurement.

Case Study: Primary Prevention

A 55‑year‑old with hypertension, TC = 210 mg/dL, HDL = 42 mg/dL, TG = 165 mg/dL. Friedewald LDL = 210 − 42 − (165/5) = 135 mg/dL → Borderline high. Non‑HDL = 168 mg/dL. TC/HDL ratio = 5.0 (moderate risk). Using Martin-Hopkins: factor for TG 165 is ~5.2 → LDL ≈ 210 − 42 − (165/5.2) ≈ 136.3 mg/dL. Clinical recommendation: lifestyle modification + statin if 10‑year ASCVD risk >7.5%. The tool’s classification matches current guidelines.

Step‑by‑Step Guide to Interpret Your Results

  1. Enter your total cholesterol, HDL, and triglycerides (mg/dL). Fasting for 9‑12 hours is ideal for Friedewald precision.
  2. Select estimation formula (Friedewald is standard; Martin‑Hopkins recommended for TG between 100‑400 mg/dL or diabetes).
  3. Click "Calculate & Analyze" – you’ll receive LDL value, non‑HDL, TC/HDL ratio, and risk category.
  4. Check the risk meter and category badge to see where your LDL falls per ACC/AHA thresholds.
  5. Discuss results with your healthcare provider for personalized risk management.

Evidence Table: LDL Risk Stratification (mg/dL)

Category LDL Range (mg/dL) Recommendation (based on AHA/ACC)
Optimal / Very High Risk < 70 Target for secondary prevention or very high ASCVD risk.
Near Optimal / Above Optimal 70 – 99 Acceptable for low‑risk individuals; lifestyle emphasis.
Borderline High 100 – 129 Consider risk enhancers; moderate‑intensity statin if risk >7.5%.
High 130 – 159 Moderate to high‑intensity statin often indicated.
Very High ≥ 160 High‑intensity statin ± ezetimibe; aggressive management.

Friedewald vs. Martin-Hopkins: Clinical Validation

Friedewald underestimates LDL by up to 10–15% when TG > 200 mg/dL and in patients with diabetes or chronic kidney disease. Martin-Hopkins, developed using the NHANES database, uses 180 different factors for TG / non‑HDL ratios, reducing systematic bias. A 2019 study in JACC confirmed that Martin-Hopkins reclassifies 12–15% of patients into more appropriate risk categories compared to Friedewald. Our calculator implements a simplified factor table (not the full 180‑factor model). For research or clinical use, please refer to the original Martin-Hopkins publication or use direct LDL measurement.

Common Misconceptions

For most individuals with TG < 400 mg/dL, calculated LDL correlates well with direct measurement (±10%). If very low LDL or high TG, direct measurement is recommended. This tool is for educational purpose only.

Friedewald formula becomes unreliable when TG > 400 mg/dL because chylomicrons alter VLDL composition. We display a warning and recommend direct LDL-C lab test.

A ratio below 3.5 indicates low cardiovascular risk; above 5 indicates higher risk. This calculator highlights the ratio to support holistic lipid assessment.

Yes, this helps monitor LDL goal achievement. For patients on high-intensity statin, the LDL target is <70 mg/dL or <55 mg/dL for very high-risk individuals according to ESC/EAS.

No – the Martin‑Hopkins option in this calculator is a simplified educational approximation using TG‑based factors. It is not the full 180‑factor NIH equation. For precise results, request a direct LDL cholesterol test from your provider.

Authoritative peer review & disclaimer – This LDL calculator is based on the National Lipid Association recommendations and Friedewald (1972) original equation. The Martin‑Hopkins factor approximation is for illustrative purposes only. Medical decisions should never rely solely on this tool. Always consult a qualified clinician for diagnosis and treatment. Last updated June 2026.

References: Friedewald WT, Levy RI, Fredrickson DS. Clin Chem. 1972;18(6):499-502; Martin SS, et al. JAMA Cardiol. 2018;3(8):749-753; 2018 AHA/ACC Multisociety Guideline; NHLBI.