AIP Calculator (Atherogenic Index of Plasma)
The Atherogenic Index of Plasma (AIP) compresses your triglycerides and HDL into a single log-transformed number — log₁₀(TG ÷ HDL-C) — that research links to the size of your LDL particles and overall cardiometabolic risk. It uses the same two lipid values as the TG/HDL ratio, but the logarithm makes it more sensitive at the extremes. One catch: the published formula and its cut-offs are defined in mmol/L, so this calculator converts for you.
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How it works
The formula — and why units matter
AIP = log₁₀(triglycerides ÷ HDL cholesterol), with both values in mmol/L. This is the most common mistake with AIP: plugging in mg/dL values directly. Because the log is taken after the division, the unit choice changes the result — the same lipid panel yields a different AIP in mg/dL than in mmol/L, and only the mmol/L version maps onto the published cut-offs (0.11 / 0.21). This calculator converts mg/dL to mmol/L internally (triglycerides ÷ 88.57, HDL ÷ 38.67), so US lab reports work as-is. If your report is already in mmol/L, convert to mg/dL first with our Cholesterol Units Converter — or compute log₁₀(TG ÷ HDL) directly.
What AIP adds beyond TG/HDL
AIP is the base-10 logarithm of the TG/HDL molar ratio — mathematically it's the same information, rescaled. The log transform spreads out the high end (where triglycerides climb steeply) and its value tracks the proportion of small, dense LDL particles in validation studies, which is why some researchers prefer it as an atherogenicity marker. For the plain ratio view, see our TG/HDL Ratio Calculator.
Where the cut-offs come from
The 0.11 / 0.21 boundaries trace back to Dobiášová's Central European cohort work and have been reused in later population studies. They are research-cohort conventions — no major guideline (ACC/AHA, ESC, NCEP) defines official AIP thresholds. Treat them as orientation, not targets.
Limitations
AIP inherits every caveat of its two inputs: non-fasting triglycerides, recent alcohol, and acute illness all distort it. It was derived and validated mostly in European adult cohorts, and its authors present it as an indirect estimate of LDL particle size — not a substitute for direct lipoprotein measurement (ApoB, LDL-P). A screening signal, not a diagnosis.
Frequently asked questions
How do I calculate my Atherogenic Index of Plasma?
Convert triglycerides and HDL to mmol/L (mg/dL triglycerides ÷ 88.57; mg/dL HDL ÷ 38.67), divide TG by HDL, then take the base-10 logarithm. Example: TG 150 mg/dL and HDL 50 mg/dL → 1.69 mmol/L ÷ 1.29 mmol/L = 1.31 → log₁₀(1.31) ≈ 0.12. The calculator above does all of this in one step.
Why does my AIP look different on other calculators?
Almost always a units issue. AIP is defined in mmol/L, but some calculators take mg/dL inputs without converting — that produces a different number that doesn't map to the published 0.11/0.21 cut-offs. Ours converts internally, so mg/dL inputs give the correct mmol/L-based AIP.
What is a normal AIP value?
In the research-cohort convention: below 0.11 is the lower-risk range, 0.11–0.21 intermediate, above 0.21 higher risk. These boundaries come from population studies (not official guidelines), so read them as orientation alongside your full lipid panel, not as targets.
Is AIP the same as the TG/HDL ratio?
It's built from the same two values — AIP is the logarithm of the TG/HDL ratio in mmol/L units. The plain ratio (in mg/dL) is more common in US practice; AIP's log scale is more common in European research and is linked to LDL particle size. They move together — see our TG/HDL Ratio Calculator for the ratio view.
Is AIP a diagnosis of heart disease risk?
No. AIP is a research-derived screening marker calculated from two routine labs. It can flag a pattern worth investigating, but cardiovascular risk assessment uses the full picture — blood pressure, glucose, smoking, family history, and sometimes direct measures like ApoB. A screening signal, not a diagnosis.
Sources
- Dobiášová M, Frohlich J. The plasma parameter log(TG/HDL-C) as an atherogenic index: correlation with lipoprotein particle size and esterification rate. Clin Biochem. 2001.
- NCEP ATP III lipid panel conventions; unit conversion factors per NCBI Bookshelf lipid conversion tables.
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.