ApoB/ApoA1 Ratio Calculator
Apolipoprotein B measures the number of atherogenic particles in your blood; apolipoprotein A1 reflects the protective ones. Their ratio compresses that balance into a single number that large cohort studies — most notably AMORIS — link to cardiovascular outcomes, often more strongly than LDL cholesterol alone.
From an advanced lipid panel
Usually reported alongside ApoB
Enter your values above to see your results.
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How it works
The formula
ApoB/ApoA1 ratio = apolipoprotein B mg/dL ÷ apolipoprotein A1 mg/dL. Both are typically reported on the same advanced lipid panel. Because each atherogenic particle (LDL, VLDL, IDL, Lp(a)) carries exactly one ApoB molecule, ApoB is effectively a particle count — and the ratio compares that count against the HDL-side protein.
What the ratio adds beyond LDL-C
LDL cholesterol measures the cargo, not the vehicles. Two people with the same LDL-C can carry very different particle numbers — and particle number is what cohort studies link most consistently to outcomes. The AMORIS study (~175,000 participants) found the ApoB/ApoA1 ratio predicted cardiovascular events more strongly than conventional cholesterol ratios.
Limitations
Reference ranges vary by sex (women typically run lower) and somewhat by population and assay. Cut-offs are cohort-derived guides, not diagnostic thresholds. Non-fasting samples have only a small effect, but trends are best compared from the same lab over time.
Frequently asked questions
What is a good ApoB/ApoA1 ratio?
In large cohort research, ratios below ~0.7 reflect a favorable lipoprotein balance, 0.7–0.9 is intermediate, and above ~0.9 is associated with higher cardiovascular event rates. Women typically run about 0.1 lower than men, so interpret your number with sex-specific context from your lab or practitioner.
Why does my doctor order ApoB instead of just LDL?
Each atherogenic particle carries one ApoB molecule, so ApoB counts particles directly. LDL cholesterol estimates the cholesterol mass inside them — which can look normal even when particle number is high, a pattern common in insulin resistance. The ratio adds the protective (ApoA1) side of the balance.
Where do I get ApoB and ApoA1 measured?
Both are standard items on advanced lipid panels offered by major US labs. They are not usually on a basic lipid panel — ask your practitioner for an ApoB or apolipoprotein panel.
Do I need to fast for this test?
ApoB and ApoA1 are only minimally affected by recent meals, unlike triglycerides. Fasting is often requested anyway because the same draw usually includes a standard lipid panel.
Is a high ApoB/ApoA1 ratio a diagnosis?
No. It is a risk marker from a single blood draw. Interpretation belongs in the context of your full panel, blood pressure, glucose metabolism, family history, and clinical assessment by a qualified practitioner.
Sources
- Walldius G, Jungner I, et al. High apolipoprotein B, low apolipoprotein A-I, and improvement in the prediction of fatal myocardial infarction (AMORIS study): a prospective study. Lancet, 2001.
- Walldius G, Jungner I. The apoB/apoA-I ratio: a strong, new risk factor for cardiovascular disease and a target for lipid-lowering therapy. J Intern Med, 2006.
- Sniderman AD, et al. Apolipoproteins versus lipids as indices of coronary risk and as targets for statin treatment. Lancet, 2003.
This calculator is for informational purposes only and is not medical advice, diagnosis, or treatment. Reference ranges are general population guidelines — always discuss your lab results with a qualified healthcare professional.