How do I calculate the ApoB/LDL ratio?

Divide ApoB by LDL cholesterol, both in mg/dL. For example, ApoB of 90 and LDL of 110 gives a ratio of 0.82 (favorable). Both values come from a standard heart panel.

What is a good ApoB/LDL ratio?

A ratio of 0.8 to 0.9 (mg/dL ÷ mg/dL) suggests cholesterol-rich, large LDL particles, which are lower risk per particle. A ratio above 1.0 suggests small, dense LDL: more particles each carrying less cholesterol, which is higher risk for the same LDL number. The ratio is a quick way to estimate LDL particle size without ordering NMR or ion mobility testing.

What does a low ApoB/LDL ratio mean?

A low ratio means relatively few particles are carrying a lot of cholesterol each: large, buoyant LDL. That pattern is generally less atherogenic than small, dense LDL at the same LDL level. It is not a guarantee of low risk on its own, so look at total ApoB and Lp(a) too.

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ApoB/LDL Ratio

The ApoB/LDL ratio is a way to estimate LDL particle size without specialized testing. Since each LDL particle carries exactly one ApoB molecule, comparing ApoB to LDL cholesterol reveals how many particles are carrying how much cholesterol. A high ApoB relative to LDL means more particles carrying less cholesterol each (small, dense LDL, which is higher risk). A low ApoB relative to LDL means fewer particles carrying more cholesterol each (large, buoyant LDL, which is lower risk).

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How much does an ApoB/LDL test cost?

ApoB/LDL is calculated rather than ordered on its own, so it comes with ApoB and lipid testing (about $95). A fuller workup adds Vitamin D ($75), hs-CRP ($69), ApoB ($50), and ApoA1 ($50). You can test ApoB/LDL and 100 other biomarkers for $190 as part of an Empirical membership.

Empirical is FSA/HSA eligible, so you can pay with pre-tax dollars. Fast for 8-12 hours beforehand for the most accurate lipid and metabolic results, and expect results in days rather than weeks.

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How does ApoB/LDL Ratio change with age?

ApoB/LDL Ratio tends to rise with age (correlation with age, r = +0.17). The chart below shows the median by 5-year age bin and a linear trend line.

ApoB/LDL Ratio rises with age, chart with median and linear trend

What can cause low ApoB/LDL?

A discordance where ApoB is high relative to LDL suggests a predominance of small, dense LDL particles. Insulin resistance, high triglycerides, and metabolic syndrome shift LDL toward smaller particles. Weight loss and triglyceride reduction (through diet, exercise, and reducing refined carbs) typically normalize this ratio.

This ratio helps explain why two people with the same LDL cholesterol can have very different cardiovascular risk. The person with more small, dense particles (higher ApoB/LDL) carries greater risk than the person with fewer large particles.

Biomarkers related to ApoB/LDL

ApoB/LDL is most highly correlated with LDL Cholesterol and Total Cholesterol. Here are the top biomarkers correlated with ApoB/LDL, based on 500,000 tests done by Empirical Health.

The percentage shows how strongly two biomarkers move together. A higher number means the relationship is stronger. Green = rises and falls together. Orange = one rises as the other falls.

Frequently asked questions about ApoB/LDL

Where to get an ApoB/LDL test near you

ApoB/LDL is drawn at 2,200+ Quest and BioReference patient service centers across the US, so there's usually one within a short drive. Browse the full directory to find the one closest to you.

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