LDL Cholesterol Calculator
Calculate LDL cholesterol with two validated equations (Friedewald & Sampson 2020), full atherogenic ratio analysis, VLDL, Non-HDL, Atherogenic Index of Plasma, and personalised cardiovascular risk classification.
Results
What is it?
LDL (Low-Density Lipoprotein) cholesterol is commonly called "bad" cholesterol because it transports cholesterol particles through the bloodstream and can deposit them into arterial walls. These deposits progressively build up as plaques — a process called atherosclerosis — narrowing arteries and dramatically increasing the risk of heart attack and stroke. LDL is the primary target of cholesterol-lowering therapy worldwide. This calculator uses two clinically validated estimation methods, automatically selecting the most accurate one for your specific lipid values: ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━ FRIEDEWALD EQUATION (1972) ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━ LDL = Total Cholesterol − HDL − (Triglycerides ÷ 5) The global standard formula, used by most clinical laboratories worldwide. The division by 5 estimates VLDL cholesterol, which is not measured directly in a standard lipid panel. Highly accurate when triglycerides are below 150 mg/dL. Becomes progressively less reliable as triglycerides rise. Valid range: TG < 400 mg/dL ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━ SAMPSON 2020 EQUATION (NIH / JAMA Cardiology) ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━ LDL = (TC / 0.948) − (HDL / 0.971) − [(TG / 8.56) + (TG × NonHDL / (2140 − TG × 0.16))] − 9.44 Developed and validated by NIH researchers (Martin Hopkins et al.) and published in JAMA Cardiology (2020). Uses a variable TG-to-VLDL conversion factor rather than the fixed "divide by 5" of Friedewald, making it significantly more accurate in two critical situations: (1) when LDL is very low (< 70 mg/dL) — exactly the range targeted by modern statin therapy, and (2) when triglycerides are elevated (150–800 mg/dL). This calculator automatically applies Sampson in both of these scenarios. ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━ WHAT THE OTHER OUTPUTS MEAN ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━ • Non-HDL Cholesterol (TC − HDL): Captures ALL atherogenic lipoproteins (LDL + VLDL + IDL). Increasingly preferred over LDL alone as a cardiovascular risk marker. Target < 130 mg/dL for most people. • VLDL Cholesterol: Estimated as TG ÷ 5. Very Low-Density Lipoprotein carries triglycerides and is also atherogenic. • TC / HDL Ratio (Castelli Index I): A classical cardiovascular risk predictor. < 3.5 is optimal; < 5.0 is acceptable; ≥ 5.0 is elevated risk. • LDL / HDL Ratio: Reflects the balance between atherogenic and protective cholesterol. < 2.5 is optimal; 2.5–3.5 is moderate; > 3.5 is increased risk. • TG / HDL Ratio: One of the best available proxies for insulin resistance and the presence of small, dense LDL particles (sdLDL), which are far more atherogenic than large, buoyant LDL particles. < 2.0 optimal; > 3.5 strongly suggests insulin resistance (in mg/dL units). • Atherogenic Index of Plasma (AIP): AIP = log₁₀(TG mmol/L ÷ HDL mmol/L). A modern, sensitive marker of cardiovascular risk that captures metabolic syndrome better than any single cholesterol value. AIP < 0.10 = low risk; 0.10–0.24 = moderate risk; > 0.24 = high risk; > 0.33 = very high risk.
How to use
You will need the results of a standard fasting lipid panel blood test — available from your doctor, clinic, or laboratory. 1. Select your unit system (mg/dL is standard in the USA and Canada; mmol/L is used in most other countries including the UK, Australia, and most of Asia). 2. Enter your three values: Total Cholesterol, HDL Cholesterol, and Triglycerides. For best accuracy, triglycerides should be from a fasting sample (9–12 hours without food). Non-fasting triglycerides can be 20–50 mg/dL higher than fasting values. 3. Select your biological sex — this affects the HDL reference range used (women naturally carry more HDL than men, so the threshold for "low HDL" differs). 4. Select your clinical risk category to personalise your LDL target: • Low/Moderate Risk (no CVD, no diabetes): Target LDL < 100 mg/dL • High Risk (diabetes or 10-year ASCVD risk ≥ 7.5%): Target LDL < 70 mg/dL • Very High Risk (established cardiovascular disease): Target LDL < 55 mg/dL The calculator will show you both formula results, the Best Estimate, how far you are from your personal target, and a full atherogenic risk profile. Note: A few labs measure LDL directly (direct LDL assay) rather than calculating it. This is labelled "Direct LDL" or "LDL-Direct" on your report. If you have a direct LDL measurement, you don't need this calculator — it's already your result.
Example scenario
Meet James, a 48-year-old man with no diabetes or heart disease. His fasting lipid panel shows: Total Cholesterol : 210 mg/dL HDL Cholesterol : 55 mg/dL (the "good" cholesterol) Triglycerides : 130 mg/dL Since triglycerides are below 150, the calculator applies the Friedewald equation and returns: LDL = 129 mg/dL As a cross-check, the Sampson 2020 formula gives 130.8 mg/dL — only 1.8 mg/dL apart, confirming the result is reliable. James has no CVD and no diabetes, so his LDL target is 100 mg/dL. He is currently 29 mg/dL above that goal. ────────────────────────────── FULL PROFILE AT A GLANCE ────────────────────────────── LDL Cholesterol 129 mg/dL Near / Above Optimal Non-HDL 155 mg/dL Borderline High (aim for < 130) TC / HDL ratio 3.82 Acceptable LDL / HDL ratio 2.35 Near Optimal TG / HDL ratio 2.36 Monitor — mild insulin resistance signal AIP 0.015 Low cardiovascular risk What does this mean? His LDL sits just below the Borderline High threshold of 130, so no medication is needed yet. The slightly elevated Non-HDL and TG/HDL numbers suggest that cutting back on refined carbohydrates and adding regular exercise could move his entire lipid profile into the healthy range without any prescription.
Pro tip
LDL RISK LEVELS (ACC/AHA) ────────────────────────────── < 100 mg/dL Optimal 100-129 mg/dL Near / Above Optimal 130-159 mg/dL Borderline High 160-189 mg/dL High 190+ mg/dL Very High (190+ may point to Familial Hypercholesterolaemia, a genetic condition — ask your doctor) LDL TARGETS BY RISK GROUP ────────────────────────────── Low risk below 116 mg/dL (3.0 mmol/L) Moderate risk below 100 mg/dL (2.6 mmol/L) High risk below 70 mg/dL (1.8 mmol/L) Very high risk below 55 mg/dL (1.4 mmol/L) Your Non-HDL target is always your LDL target plus 30 mg/dL. WHEN FRIEDEWALD IS NOT RELIABLE ────────────────────────────── The Friedewald formula becomes inaccurate when triglycerides are 400 mg/dL or higher. The Sampson 2020 formula works up to 800 mg/dL. Above 800 mg/dL, only a direct lab measurement is reliable. This calculator automatically switches formulas and flags any validity concern for you. LIFESTYLE CHANGES THAT LOWER LDL ────────────────────────────── Reduce saturated fat (< 7% of calories) -8 to -10% Add soluble fibre (oats, beans, psyllium) -5 to -7% Plant sterols or stanols (2 g per day) -8 to -10% Aerobic exercise, 150 min per week -3 to -6% Eliminate trans fats completely -5 to -8% Lose 10 pounds (4.5 kg) -5 to -8% All of the above combined up to -30% ABOUT HDL (THE "GOOD" CHOLESTEROL) ────────────────────────────── HDL at 60 mg/dL or above is protective — it actually cancels out one other cardiovascular risk factor. HDL below 40 mg/dL (men) or below 50 mg/dL (women) is itself a risk factor for heart disease, regardless of your LDL level.