🫀 LDL Cholesterol Calculator Friedewald Formula
Enter total cholesterol, HDL, and triglycerides to compute LDL-C, non-HDL-C, VLDL, and the TC/HDL ratio.
Units: mg/dL
Units: mg/dL
Units: mg/dL (fasting preferred)
📊 Results
📋 LDL-C Reference Ranges (NCEP ATP III)
| Category | LDL (mg/dL) | Interpretation |
|---|---|---|
| Optimal | < 100 | Low atherosclerotic risk; ideal in most adults |
| Near Optimal | 100 – 129 | Acceptable for low-risk adults without CV disease |
| Borderline | 130 – 159 | Lifestyle change indicated; consider statin if additional risk factors |
| High | 160 – 189 | Pharmacotherapy typically recommended |
| Very High | ≥ 190 | Statin therapy indicated; evaluate for familial hypercholesterolemia |
📐 Formulas
Friedewald equation
LDL = TC − HDL − (TG / 5)
Non-HDL cholesterol
Non-HDL = TC − HDL
VLDL cholesterol
VLDL = TG / 5
TC/HDL ratio
Ratio = TC / HDL
* Inaccurate when TG ≥ 400 mg/dL — use Martin-Hopkins or direct LDL instead.
LDL = TC − HDL − (TG / 5)
Non-HDL cholesterol
Non-HDL = TC − HDL
VLDL cholesterol
VLDL = TG / 5
TC/HDL ratio
Ratio = TC / HDL
* Inaccurate when TG ≥ 400 mg/dL — use Martin-Hopkins or direct LDL instead.
❓ Frequently Asked Questions
What is LDL cholesterol? ▼
Low-density lipoprotein (LDL) carries cholesterol from the liver to peripheral tissues. Elevated LDL drives atherosclerotic plaque formation and is the primary modifiable lipid risk factor for myocardial infarction and ischemic stroke. Lower LDL consistently reduces cardiovascular events in randomized trials.
What are the limits of the Friedewald formula? ▼
The equation underestimates LDL when triglycerides exceed 400 mg/dL because VLDL-C can no longer be approximated as TG/5. It is also unreliable in type III hyperlipidemia and in severely non-fasting samples. The Martin-Hopkins adjustable-factor equation (2013) improves accuracy across the TG spectrum; direct LDL measurement is the gold standard when results will drive therapy.
What is non-HDL cholesterol? ▼
Non-HDL-C = Total cholesterol − HDL, capturing all atherogenic lipoproteins (LDL, VLDL, IDL, lipoprotein(a)). It is a guideline-endorsed secondary target that outperforms LDL in non-fasting samples and in patients with hypertriglyceridemia or diabetes. Target: Non-HDL-C < LDL target + 30 mg/dL.
What is a healthy TC/HDL ratio? ▼
Below 3.5 is considered ideal, < 5.0 acceptable in men, < 4.5 in women. The ratio summarizes risk in a single number but is now secondary to absolute LDL-C and non-HDL-C targets in ACC/AHA and ESC/EAS guidelines.
🔗 Related Calculators
About LDL
Low-density lipoprotein (LDL) is often called the "bad" cholesterol. Elevated LDL drives plaque buildup in arterial walls (atherosclerosis), a major cause of myocardial infarction and ischemic stroke.
The NCEP ATP III and ACC/AHA 2018 guidelines recommend individualizing LDL targets based on cardiovascular risk rather than applying a single population threshold.
✅ Action Guide by LDL Level
Optimal LDL < 100 mg/dL
Maintain a heart-healthy diet, regular aerobic exercise, smoking cessation. Re-screen every 4–6 years in low-risk adults.
Near Optimal LDL 100–129 mg/dL
Begin dietary modification (saturated fat < 7% of calories, fiber 25+ g/day). Evaluate the 10-year ASCVD risk score.
Borderline LDL 130–159 mg/dL
Aggressive lifestyle change. ≥ 150 min/week moderate-intensity exercise. Consider moderate-intensity statin if 10-year ASCVD ≥ 7.5% or additional risk enhancers are present.
High LDL 160–189 mg/dL
Statin therapy typically recommended. Consider evaluation for secondary causes (hypothyroidism, cholestasis, nephrotic syndrome) before labeling as primary.
Very High LDL ≥ 190 mg/dL
High-intensity statin indicated regardless of ASCVD score. Screen for familial hypercholesterolemia (Dutch Lipid Clinic criteria) and consider cascade screening of first-degree relatives.
🔗 Next Steps
- → Non-HDL cholesterol — a more complete atherogenic risk marker (shown in results above)
- → Blood pressure — hypertension + dyslipidemia compound CV risk
- → HbA1c — diabetes frequently coexists with dyslipidemia
- → eGFR — CKD is a risk-enhancing factor for statin initiation
⚠️ Disclaimer
This calculator is provided for educational and reference purposes only. It does not replace clinical judgment and should not be used to guide direct patient care. No warranty is made regarding accuracy; the operator assumes no liability for direct or indirect harm arising from use.
References: Friedewald WT, Levy RI, Fredrickson DS. Estimation of the concentration of low-density lipoprotein cholesterol in plasma. Clin Chem. 1972;18(6):499-502. · Martin SS et al. JAMA. 2013. · Grundy SM et al. 2018 AHA/ACC Cholesterol Guideline. · Mach F et al. 2019 ESC/EAS Dyslipidaemia Guidelines.
This calculator is provided for educational and reference purposes only. It does not replace clinical judgment and should not be used to guide direct patient care. No warranty is made regarding accuracy; the operator assumes no liability for direct or indirect harm arising from use.
References: Friedewald WT, Levy RI, Fredrickson DS. Estimation of the concentration of low-density lipoprotein cholesterol in plasma. Clin Chem. 1972;18(6):499-502. · Martin SS et al. JAMA. 2013. · Grundy SM et al. 2018 AHA/ACC Cholesterol Guideline. · Mach F et al. 2019 ESC/EAS Dyslipidaemia Guidelines.