Calculate the LDL-C/ApoB ratio from lipid lab values in mg/dL or mmol/L and g/L, with low, typical, or high interpretation guidance.
Educational use only; not medical advice. Use LDL-C and ApoB values from a recent laboratory blood test. Do not use this calculator to diagnose, treat, or change medications—discuss results with a qualified clinician.
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LDL-C/ApoB Ratio Formula
The LDL-C/ApoB ratio compares the amount of LDL cholesterol to the amount of apolipoprotein B. The calculator first puts both values into compatible units, then divides LDL-C by ApoB.
LDL\text{-}C/ApoB\ Ratio = LDL\text{-}C \div ApoB- LDL-C = low-density lipoprotein cholesterol
- ApoB = apolipoprotein B
- LDL-C/ApoB Ratio = LDL-C divided by ApoB, after both values are expressed in compatible mass units
For US units, both LDL-C and ApoB are entered in mg/dL, so the calculator uses the values directly:
Ratio = LDL\text{-}C_{mg/dL} \div ApoB_{mg/dL}For international units, LDL-C is entered in mmol/L and ApoB is entered in g/L. The calculator converts them before calculating the ratio:
LDL\text{-}C_{mg/dL} = LDL\text{-}C_{mmol/L} * 38.67ApoB_{mg/dL} = ApoB_{g/L} * 100Ratio = (LDL\text{-}C_{mmol/L} * 38.67) \div (ApoB_{g/L} * 100)- US units mode calculates the ratio from LDL-C in mg/dL and ApoB in mg/dL.
- International units mode converts LDL-C from mmol/L to mg/dL and ApoB from g/L to mg/dL, then calculates the same ratio.
- Interpretation band labels the result as low, typical, or higher based on the ratio cutoffs shown below.
LDL-C/ApoB Ratio Interpretation
| Ratio result | Calculator label | General meaning |
|---|---|---|
| Less than 1.2 | Low ratio | More ApoB particles per unit of LDL cholesterol, often associated with smaller, denser LDL particles. |
| 1.2 to 1.4 | Typical ratio | A range commonly seen on standard lipid panels. |
| Greater than 1.4 | Higher ratio | Fewer ApoB particles relative to LDL cholesterol, often associated with larger, more buoyant LDL particles. |
Common Unit Conversions
| Lab value | Entered unit | Conversion used |
|---|---|---|
| LDL-C | mmol/L | Multiply by 38.67 to get mg/dL |
| ApoB | g/L | Multiply by 100 to get mg/dL |
| LDL-C and ApoB | mg/dL | No conversion needed |
Example Calculations
Example 1: US units
If your LDL-C is 120 mg/dL and your ApoB is 95 mg/dL:
Ratio = 120 \div 95 = 1.26
The LDL-C/ApoB ratio is 1.26, which falls in the typical range used by the calculator.
Example 2: International units
If your LDL-C is 3.1 mmol/L and your ApoB is 0.95 g/L:
LDL\text{-}C = 3.1 * 38.67 = 119.88\ mg/dLApoB = 0.95 * 100 = 95\ mg/dL
Ratio = 119.88 \div 95 = 1.26
The LDL-C/ApoB ratio is 1.26.
FAQ
What does the LDL-C/ApoB ratio tell you?
The LDL-C/ApoB ratio gives a rough comparison between the cholesterol carried in LDL particles and the number of ApoB-containing particles. Since each LDL particle usually carries one ApoB molecule, ApoB can reflect particle number, while LDL-C reflects cholesterol mass. A lower ratio can suggest more particles for the same amount of LDL cholesterol.
Is a higher LDL-C/ApoB ratio always better?
Not necessarily. A higher ratio may suggest fewer ApoB particles relative to LDL cholesterol, but it does not mean your cardiovascular risk is low by itself. LDL-C, ApoB, non-HDL cholesterol, triglycerides, HDL-C, blood pressure, diabetes status, smoking, age, and medical history can all affect risk interpretation.
Why do the units matter?
The ratio only works when LDL-C and ApoB are compared in compatible units. If LDL-C is in mmol/L and ApoB is in g/L, the values must be converted before division. Using the wrong unit mode can give an incorrect result.
