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CardiologyLDL/HDL Ratio

LDL-to-HDL Cholesterol Ratio Calculator

Calculate the unitless LDL-C-to-HDL-C ratio from one same-panel lipid profile, with method-aware arithmetic and current-guideline limitations.

Content updated: View sources

QuickMedCalc is developed and maintained by an independent developer. Medical content is not independently reviewed by a physician.

Formula and medical content are based on the references listed on this page. See sources, About, and Sources and Review Process.

One unit applies to same-panel LDL-C and HDL-C. A true unit switch clears both values rather than converting them.

Use the reported value from the same lipid panel. This page does not identify how LDL-C was measured or estimated.

Use the reported value from the same lipid panel. This page does not identify how LDL-C was measured or estimated.

About

This page calculates only LDL-C ÷ HDL-C from LDL-C and HDL-C reported on the same lipid panel and clinical time point. The output is a unitless arithmetic quotient. It is not a directly measured lipoprotein or particle value, a PREVENT result, a personal event probability, a diagnosis, a universal treatment target, or a treatment decision. The page uses the LDL-C that was submitted and cannot know whether it was estimated or measured; it does not calculate any other lipid ratio or choose a test, medicine, dose, or treatment.[7, 9]

Lemieux and colleagues studied fasting measurements in 2,103 middle-aged men in the Quebec Cardiovascular Study. Their comparison of ratios was especially relevant to an overweight, hyperinsulinemic, high-triglyceride and low-HDL-C phenotype; it does not establish a website-wide threshold or imply that TC/HDL-C is always superior. Kinosian described historical multi-cohort prediction comparisons, while Ridker studied 15,632 initially healthy United States women aged 45 years or older for about 10 years. These are population associations and historical prediction findings, not a personal probability from one submitted quotient.[1, 2, 3]

PREVENT uses non-HDL-C and HDL-C separately with other clinical predictors; it does not use LDL-C or the LDL-C/HDL-C ratio as a base-model lipid input. The 2026 dyslipidemia guideline and its correction emphasize absolute lipid values and complete risk pathways rather than a universal LDL-C/HDL-C treatment target. ADLM guidance and its correction describe laboratory reporting and method limits. This page does not convert a ratio to a risk percentage or target. It does not calculate a risk percentage.[5, 6, 7, 8, 9, 10]

Formula

LDL-C/HDL-C ratio = LDL-C ÷ HDL-C. Use same-panel values in the same selected unit; the result is dimensionless.[1, 9]
120 mg/dL ÷ 40 mg/dL = 3.00; 60 mg/dL ÷ 20 mg/dL = 3.00. Zero LDL-C and LDL-C below HDL-C remain valid arithmetic when HDL-C is positive.
Friedewald, Martin/Hopkins, Sampson/NIH, direct homogeneous LDL-C, and beta-quantification are different ways a laboratory may report LDL-C. This page does not re-estimate or convert the submitted numerator.[12, 13, 14]
No fixed ratio cutoff, risk probability, PREVENT calculation, treatment target, or medication output is generated. This page does not define a treatment target.

Interpretation

Same ratio, different absolute lipid values

Arithmetic examples only; not reference values, goals, or treatment comparisons.
LDL-CHDL-CRatioWhat is lost
120 mg/dL40 mg/dL3.00Absolute concentrations
60 mg/dL20 mg/dL3.00Absolute concentrations

The two ratios match while both absolute values differ. The quotient cannot reconstruct total cholesterol, non-HDL-C, triglycerides, ApoB, LDL particle number, or Lp(a). These examples are arithmetic only and are not a user-result classifier.[1, 3, 9]

Historical evidence and current role

Source-specific context; no row assigns a result category.
EvidenceWhat it contributesBoundary
Lemieux 2001Fasting Quebec Cardiovascular Study data from 2,103 middle-aged men and a defined metabolic phenotype.not a universal threshold or conclusion for every population.
Kinosian 1994Historical multi-cohort comparison of lipid levels and ratios for prediction.Historical performance is not a current treatment target.
Ridker 2005Observed associations in 15,632 initially healthy United States women aged 45 years or older followed for about 10 years.A cohort association is not a personal event probability.
Current roleAbsolute lipids and complete multivariable risk pathways remain necessary.No universal LDL-C/HDL-C treatment target is assigned.

The historical studies do not justify a modern ladder or a comparison of a submitted result with a fixed threshold.[1, 2, 3, 7, 8]

PREVENT uses different inputs

PREVENT uses non-HDL-C and HDL-C as separate lipid predictors alongside age, blood pressure, kidney, diabetes, smoking, and treatment variables. It does not use LDL-C as a base-model lipid input or the LDL-C/HDL-C ratio, and the same ratio can accompany different non-HDL-C and clinical values. This page cannot create a PREVENT percentage.[5, 6]

LDL-C methods can change the numerator

Static method context; none is implemented here.
MethodSource-specific descriptionThis page
FriedewaldHistorical fixed-divisor estimate from a standard lipid profile.Does not recalculate it.
Martin/HopkinsUses a variable triglyceride-to-VLDL-C factor.Does not recognize or convert it.
Sampson/NIHUses an independent nonlinear estimation equation.Does not implement it.
Direct homogeneous LDL-C assayAutomated assay measurement, distinct from reference procedures.Uses the submitted report.
β-quantificationA reference measurement pathway, not the same as a routine direct assay.Cannot identify the method.

Method differences can change the LDL-C numerator and therefore the quotient. A homogeneous direct LDL-C assay is distinct from beta-quantification. The page does not recommend a method, re-estimate LDL-C, or treat sequential reports from different methods as automatically interchangeable.[9, 10, 12, 13, 14]

HDL-C association is not a causal guarantee

Higher HDL-C often accompanies lower event rates in observational data, but concentration does not summarize HDL function or prove causality. Voight’s Mendelian-randomisation analysis found that some genetically mediated HDL-C increases did not produce the expected myocardial- infarction protection. Lowering this quotient by changing HDL-C is not evidence of treatment benefit, and very high HDL-C is not unlimited protection. No threshold or U-shaped classification is generated.[3, 4]

Different lipid measures are not interchangeable

Static comparison; this runtime returns only LDL-C/HDL-C.
MeasureMeaningCalculated here?
LDL-C/HDL-CLDL-C divided by HDL-C; unitless.Yes
TC/HDL-CTotal cholesterol divided by HDL-C; a different numerator and page.No
Non-HDL-CTotal cholesterol minus HDL-C; concentration with units.No
Non-HDL-C/HDL-CSometimes called an atherogenic coefficient; different numerator.No
TG/HDL-CTriglycerides divided by HDL-C; a different quotient.No
Atherogenic Index of PlasmaA research convention involving log10(TG/HDL-C) in molar units.No
ApoB/ApoA-IIndependent apolipoprotein measurements.No
LDL particle numberParticle-related laboratory measurement.No

These measures answer different questions. This page does not recommend ordering or substituting any of them.[3, 9, 10]

Fasting, nonfasting, and special contexts

Routine lipid profiles can often be collected without fasting, but high triglycerides, inherited lipid disorders, childhood, pregnancy, acute illness, diabetes, CKD, familial hypercholesterolemia, chylomicronemia, type III dysbetalipoproteinemia, cholestatic disease or LpX, treatment changes, extreme reported values, and method changes may limit interpretation or prompt a clinician to choose a particular collection protocol. This page does not collect fasting status, choose repeat testing, or create a special diagnostic pathway.[9, 10, 11]

Both entries must use the same unit and same panel. The page does not combine different dates, laboratories, treatment states, or reported methods.

What the result represents

The quotient preserves a relative relationship between two same-panel concentrations and loses their absolute values. LDL-C 120/HDL-C 40 and 60/20 both display 3.00, while LDL-C 0 divided by positive HDL-C displays 0.00 and LDL-C 40 divided by HDL-C 80 displays 0.50. LDL-C 50 divided by HDL-C 50 displays 1.00. These are valid arithmetic examples, not statements about risk, protection, or goals.[1, 9]

Input units

Choose mg/dL or mmol/L once for the lipid panel and enter both values in that same unit. The runtime does not convert units, infer a missing unit, or silently reinterpret an existing number after a true unit switch.

Worked example

  1. Read LDL-C and HDL-C from one submitted lipid panel.
  2. Confirm that both strings use the selected identical concentration unit.
  3. Allow LDL-C to be zero or below HDL-C when HDL-C is positive.
  4. Divide at full precision and format the unitless result to two decimals.

The displayed number is an arithmetic audit, not a risk estimate, target, or treatment response.

Applicable population

This is a transparent arithmetic tool for people with contemporaneous reported LDL-C and HDL-C results. It does not decide whether a ratio is appropriate for a child, pregnancy, acute illness, inherited lipid disorder, or another clinical context.

Interpretation limitations

The page cannot identify the LDL-C method, reconstruct non-HDL-C or particles, measure HDL function, calculate PREVENT, diagnose disease, establish an individual goal, choose a test or medicine, or determine treatment benefit. Reported very low LDL-C may also reflect assay limits, estimation method, or laboratory reporting rules; a zero arithmetic quotient does not prove absent particles or absent cardiovascular risk.

references

The numbered references separate primary studies, corrections, current guidance, fasting guidance, and LDL-C method papers so each claim can be checked against its source.

formulas

The only runtime formula is LDL-C ÷ HDL-C. No other ratio, risk model, threshold ladder, or treatment calculation is implemented.

References

  1. Lemieux I, Lamarche B, Couillard C, et al. Total cholesterol/HDL cholesterol ratio vs LDL cholesterol/HDL cholesterol ratio as indices of ischemic heart disease risk in men. Arch Intern Med. 2001;161(22):2685–2692. PMID 11732933. DOI 10.1001/archinte.161.22.2685.
  2. Kinosian B, Glick H, Garland G. Cholesterol and coronary heart disease: predicting risks by levels and ratios. Ann Intern Med. 1994;121(9):641–647. PMID 7944071. DOI 10.7326/0003-4819-121-9-199411010-00002.
  3. Ridker PM, Rifai N, Cook NR, Bradwin G, Buring JE. Non-HDL cholesterol, apolipoproteins A-I and B100, standard lipid measures, lipid ratios, and CRP as risk factors for cardiovascular disease in women. JAMA. 2005;294(3):326–333. PMID 16030277. DOI 10.1001/jama.294.3.326.
  4. Voight BF, Peloso GM, Orho-Melander M, et al. Plasma HDL cholesterol and risk of myocardial infarction: a Mendelian randomisation study. Lancet. 2012;380(9841):572–580. PMID 22607825. PMCID PMC3419820. DOI 10.1016/S0140-6736(12)60312-2.
  5. Khan SS, Matsushita K, Sang Y, et al. Development and Validation of the American Heart Association's PREVENT Equations. Circulation. 2024;149(6):430–449. PMID 37947085. PMCID PMC10910659. DOI 10.1161/CIRCULATIONAHA.123.067626.
  6. Correction to: Development and Validation of the American Heart Association's PREVENT Equations. Circulation. 2024. PMID 38466792. DOI 10.1161/CIR.0000000000001230.
  7. Blumenthal RS, Morris PB, Gaudino M, et al. 2026 ACC/AHA/AACVPR/ABC/ACPM/ADA/AGS/APhA/ASPC/NLA/PCNA Guideline on the Management of Dyslipidemia. Circulation. 2026;153:e1154–e1276. PMID 41824552. DOI 10.1161/CIR.0000000000001423.
  8. Correction to: 2026 ACC/AHA/AACVPR/ABC/ACPM/ADA/AGS/APhA/ASPC/NLA/PCNA Guideline on the Management of Dyslipidemia. Circulation. 2026. PMID 42330109. DOI 10.1161/CIR.0000000000001457.
  9. Cao J, Donato L, El-Khoury JM, et al. ADLM Guidance Document on the Measurement and Reporting of Lipids and Lipoproteins. J Appl Lab Med. 2024;9(5):1040–1056. PMID 39225455. DOI 10.1093/jalm/jfae057.
  10. Correction to: ADLM Guidance Document on the Measurement and Reporting of Lipids and Lipoproteins. J Appl Lab Med. 2025. PMID 40172951. DOI 10.1093/jalm/jfaf021.
  11. Nordestgaard BG, Langsted A, Mora S, et al. Fasting is not routinely required for determination of a lipid profile. Eur Heart J. 2016;37:1944–1958. PMID 27122601. PMCID PMC4929379. DOI 10.1093/eurheartj/ehw152.
  12. Friedewald WT, Levy RI, Fredrickson DS. Estimation of the concentration of low-density lipoprotein cholesterol in plasma, without use of the preparative ultracentrifuge. Clin Chem. 1972;18(6):499–502. PMID 4337382.
  13. Martin SS, Blaha MJ, Elshazly MB, et al. Comparison of a novel method vs the Friedewald equation for estimating low-density lipoprotein cholesterol levels from the standard lipid profile. JAMA. 2013;310(19):2061–2068. PMID 24240933. PMCID PMC4226221. DOI 10.1001/jama.2013.280532.
  14. Sampson M, Ling C, Sun Q, et al. A New Equation for Calculation of Low-Density Lipoprotein Cholesterol in Patients With Normolipidemia and/or Hypertriglyceridemia. JAMA Cardiol. 2020;5(5):540–548. PMID 32101259. PMCID PMC7240357. DOI 10.1001/jamacardio.2020.0013.

FAQ

Related Calculators

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Calculate the unitless total cholesterol-to-HDL-C ratio from one same-panel lipid profile, with exact arithmetic and current-guideline limitations.

Non-HDL-C

Calculate non-HDL cholesterol from total cholesterol minus HDL-C from the same lipid panel, with unit-safe arithmetic and guideline-context limitations.

Disclaimer

Educational and informational reference only. Not intended to replace professional medical advice, diagnosis, treatment, or independent verification.