Friedewald LDL Calculator
Friedewald LDL cholesterol calculator from total cholesterol, HDL, and triglycerides. The classic 1972 formula used in millions of US lipid panels. Educational only — discuss with your doctor.
Friedewald LDL Calculator
Please tick the acknowledgement above before calculating.
How to use the Friedewald LDL calculator
Get a fasting lipid panel
The Friedewald formula requires fasting total cholesterol, HDL-C, and triglycerides (no food for 9-12 hours before the blood draw). Find these values on your CMP / lipid panel report. Most labs report in mg/dL (US); to convert from mmol/L, multiply cholesterol by 38.67 and TG by 88.57.
Enter all three values
Total cholesterol (mg/dL): the sum of LDL + HDL + VLDL. HDL-C: the "good" cholesterol. Triglycerides: fat circulating in blood. All from the same fasting blood draw.
Check triglyceride threshold
The Friedewald formula is INVALID when triglycerides ≥ 400 mg/dL because VLDL estimation becomes unreliable. At high triglycerides, request a direct LDL measurement (β-quantification or Martin-Hopkins equation).
Acknowledge the disclaimer
Tick the acknowledgement checkbox. This computes an ESTIMATE — clinical decisions require full lab work + physician interpretation in context (medical history, family history, ASCVD risk score).
Read LDL + category + discuss
AHA/ACC 2018 categories: Optimal <100, near optimal 100-129, borderline 130-159, high 160-189, very high ≥190. Targets: established ASCVD <70; very high risk <55. Lifestyle + statin decisions are individualised — discuss with your cardiologist or PCP.
The Friedewald formula — 50 years of estimated LDL
The Friedewald formula, published in 1972 by William T. Friedewald, Robert I. Levy, and Donald S. Fredrickson at the NIH, has been the workhorse method for estimating LDL cholesterol in clinical labs worldwide for over five decades. The math is deceptively simple: LDL = Total Cholesterol − HDL − (Triglycerides / 5) in mg/dL. The TG/5 term estimates VLDL cholesterol based on the typical 5:1 ratio of TG to cholesterol in VLDL particles. The formula spread because it requires no special lab equipment — just a standard fasting lipid panel. Hundreds of millions of US lipid panels have used it. Today direct LDL measurement (β-quantification or Martin-Hopkins) is available but more expensive; Friedewald remains the standard reporter algorithm in routine practice.
When Friedewald breaks down
Two known limitations. (1) Triglycerides ≥ 400 mg/dL: VLDL composition changes at high TG, making the TG/5 assumption unreliable. The 2013 NLA guidelines + 2018 AHA/ACC explicitly state Friedewald is invalid above 400 mg/dL. Use direct LDL or the newer Martin-Hopkins 2013 formula. (2) Very low LDL (<70 mg/dL): Friedewald systematically underestimates LDL by 10-25% at low ranges — clinically meaningful for patients on high-intensity statins targeting LDL <55. The Martin-Hopkins formula (which uses a TG/adjustable-factor instead of TG/5) is more accurate at these ranges. Both 2013 Martin-Hopkins and 2020 Sampson-Martin (NIH update) are increasingly replacing Friedewald in tertiary cardiology centers.
Friedewald 1972 remains the most-used clinical lab algorithm in history. 50+ years, hundreds of millions of lipid panels, billions of cardiology decisions — all from a 3-author paper in Clinical Chemistry.
LDL targets in 2026
Current AHA/ACC 2018 guidelines (still in force) categorise LDL: <100 optimal, 100-129 near-optimal, 130-159 borderline, 160-189 high, ≥190 very high. Treatment thresholds: established ASCVD (post-MI, post-stroke, multi-vessel CAD) target LDL <70 with high-intensity statin. Very high risk (multiple recent events, recurrent MI) target LDL <55 — often requires statin + ezetimibe + PCSK9 inhibitor combo. Primary prevention: 10-year ASCVD risk >7.5% generally triggers statin discussion. Familial hypercholesterolemia: LDL ≥190 untreated suggests FH — genetic testing + intensive treatment.
ASEAN cholesterol context
ASEAN cardiovascular disease patterns: Singapore has one of the world\'s highest rates of premature coronary disease per capita; lipid screening starts at age 18 for high-risk groups (Asians have higher LDL response to saturated fat than Caucasians). Malaysia, Thailand, Indonesia: rapidly rising CVD burden tied to dietary transition + urbanisation. Hong Kong: lower CVD rates but rising statin prescribing. Friedewald is used universally in ASEAN labs; recent Indian + Singapore studies suggest Martin-Hopkins is more accurate for the lower LDL ranges common in plant-forward Asian diets.
10 Things to Know About Friedewald LDL
LDL = TC − HDL − (TG/5). The 1972 Friedewald formula. Three-author NIH paper became the global standard.
The TG/5 term estimates VLDL cholesterol. Based on typical 5:1 TG-to-cholesterol ratio in VLDL particles.
INVALID at TG ≥ 400 mg/dL. VLDL composition shifts; estimation breaks down. Use direct LDL or Martin-Hopkins.
Underestimates LDL by 10-25% at low ranges (<70 mg/dL). Matters for high-intensity statin patients targeting LDL <55.
Fasting required (9-12 hours): non-fasting elevates triglycerides + invalidates VLDL estimate.
AHA/ACC categories: <100 optimal, 100-129 near-optimal, 130-159 borderline, 160-189 high, ≥190 very high.
Established ASCVD target: LDL <70. Very high risk: LDL <55. Both require intensive statin.
Martin-Hopkins (2013): newer, uses adjustable VLDL factor instead of TG/5. More accurate at low LDL ranges.
Non-HDL cholesterol (TC − HDL) is an alternative — works regardless of TG level. Target: 30 mg/dL above LDL target.
Familial hypercholesterolemia: untreated LDL ≥ 190 mg/dL suggests FH. Genetic testing + intensive treatment.
Frequently asked questions
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Most US labs report Friedewald-calculated LDL (it\'s the default). This calculator lets you verify the math + understand the components. Also useful for: tracking changes across labs (different reporting algorithms), checking the Martin-Hopkins or non-HDL alternatives, understanding what your numbers mean before your doctor visit. Some labs (particularly tertiary cardiology centers) increasingly use Martin-Hopkins or direct LDL — check your lab report\'s methodology note.
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Non-HDL-C = Total Cholesterol − HDL-C. Includes LDL + VLDL + IDL + Lp(a) — all the atherogenic particles. Advantages: (1) doesn\'t require fasting, (2) works at any TG level, (3) captures atherogenic particles Friedewald-LDL misses. AHA recommends non-HDL target = LDL target + 30 mg/dL. For LDL goal <100, non-HDL goal <130. Increasingly used as a primary or supplementary metric in cardiology.
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Triglycerides rise dramatically after meals (especially fatty meals), inflating the TG/5 VLDL estimate + producing falsely-low LDL via Friedewald. Total cholesterol + HDL don\'t change much post-meal; only TG matters for fasting. The 2018 AHA/ACC + 2019 ESC/EAS guidelines now allow NON-fasting lipid panels for routine screening (most patients), but require fasting for: TG>400 follow-up, statin titration, suspected FH workup.
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The 2013 Johns Hopkins update to Friedewald. Instead of TG/5 (constant), it uses an adjustable factor based on the patient\'s actual TG and non-HDL-C, looked up in a 180-cell table. Result: 30-40% reduction in LDL classification errors vs Friedewald, especially at low LDL and high TG. Cleveland Clinic, Mayo, Johns Hopkins, and many tertiary cardiology centers have switched. Friedewald remains valid for most outpatient screening.
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Technically yes (the <400 cutoff is a hard rule), but Friedewald accuracy degrades progressively from TG 200-400. At TG 380, your calculated LDL could be 10-20% off the true value. Better practice: TG > 200 → use Martin-Hopkins or non-HDL-C; TG > 400 → mandatory direct LDL or Martin-Hopkins. Discuss with your physician.
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LDL:HDL ratio is an older CVD risk indicator. Below 3.5 = optimal; 3.5-5.0 = average; >5.0 = increased risk. Less used in modern guidelines vs absolute LDL or non-HDL targets. Total cholesterol:HDL ratio is similar; below 5 = optimal, above 5 = elevated risk. Useful as quick screening but absolute LDL value + ASCVD risk score dominate clinical decisions.
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Depends on your overall ASCVD risk, not just LDL. Three patients with LDL 130: (a) 40-year-old healthy non-smoker, low risk — lifestyle first, no statin needed. (b) 60-year-old smoker with diabetes, high risk — high-intensity statin. (c) 70-year-old post-MI, very high risk — high-intensity statin + ezetimibe + possibly PCSK9i. The ACC ASCVD Risk Estimator+ at tools.acc.org gives the 10-year + lifetime risk based on multiple inputs.
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Cholesterol (TC, HDL, LDL): multiply mmol/L by 38.67 to get mg/dL. Triglycerides: multiply mmol/L by 88.57. Example: TC 5.2 mmol/L × 38.67 = 201 mg/dL. Most ASEAN, European, and UK labs report mmol/L; US labs use mg/dL. Some calculators have a unit toggle — this one uses mg/dL; convert before entering.
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No. TC, HDL, TG values — every input stays in your browser. The Friedewald computation runs entirely client-side. Open DevTools → Network and confirm zero outbound requests. Safe for personal lipid panel analysis.
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Primary source: Friedewald WT, Levy RI, Fredrickson DS. Clin Chem 1972;18(6):499-502. AHA/ACC 2018 Cholesterol Guidelines + 2022 update. ESC/EAS 2019 Dyslipidemia Guidelines. ACC ASCVD Risk Estimator+ (tools.acc.org) for 10-year risk computation. Martin-Hopkins 2013 update: JAMA 2013;310:2061-2068.
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