HOMA Index Calculator — HOMA-IR and Insulin Resistance
Calculator
HOMA Index Calculator
Calculate HOMA-IR, HOMA-β and QUICKI from fasting glucose and insulin from the same blood draw, in mg/dL or mmol/L
The calculator applies Matthews' HOMA1 model (1985): HOMA-IR = glucose × insulin / 405 with glucose in mg/dL (/ 22.5 in mmol/L) and insulin in µU/mL, HOMA-β = 360 × insulin / (glucose − 63) in mg/dL (20 × insulin / (glucose − 3.5) in mmol/L), plus Katz's QUICKI (2000). You need glucose and insulin from the same fasting blood draw. This is an informational tool: there is no universal HOMA-IR threshold, values depend on the laboratory's insulin assay and interpretation is up to your doctor. The calculation is not a diagnosis of insulin resistance and does not replace your lab report or a clinical assessment.
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How the HOMA index calculator works
The HOMA index estimates, from just two blood values, how well the body responds to insulin. You need a glucose and an insulin level measured on the same fasting blood draw: from these the model derives HOMA-IR, which describes insulin resistance, and HOMA-β, which describes the ability of the pancreatic beta cells to secrete insulin. This free calculator computes both and adds QUICKI, a second insulin sensitivity index built on the same two values. Everything happens in your browser: the numbers you type are not sent to any server.
You can work in mg/dL, the unit almost always used in Italian lab reports, or in mmol/L; for insulin you can use µU/mL (identical to mU/L) or pmol/L. The calculator applies the published formula for the chosen unit, so the result does not change depending on how you enter the data.
The HOMA and QUICKI formulas
The model was published by Matthews and colleagues in Diabetologia in 1985. The approximations everyone calls “HOMA” are these, with insulin in µU/mL:
| Index | Glucose in mg/dL | Glucose in mmol/L |
|---|---|---|
| HOMA-IR (insulin resistance) | glucose × insulin / 405 | glucose × insulin / 22.5 |
| HOMA-β (beta-cell function, %) | 360 × insulin / (glucose − 63) | 20 × insulin / (glucose − 3.5) |
| QUICKI (insulin sensitivity) | 1 / (log₁₀ insulin + log₁₀ glucose in mg/dL) | convert to mg/dL first |
The two columns say the same thing: 405 is 22.5 × 18, 63 is 3.5 × 18 and 360 is 20 × 18, where 18 is the factor that converts mmol/L to mg/dL. HOMA-β is not defined when fasting glucose is equal to or below 63 mg/dL (3.5 mmol/L), because the denominator becomes zero or negative: in that case the calculator shows HOMA-IR and QUICKI and states that HOMA-β cannot be calculated, instead of printing a meaningless number.
Calculation example
Lab report with fasting glucose 95 mg/dL and fasting insulin 10 µU/mL:
| Item | Calculation | Result |
|---|---|---|
| HOMA-IR | 95 × 10 / 405 | 2.35 |
| HOMA-β | 360 × 10 / (95 − 63) | 112.5 % |
| QUICKI | 1 / (log₁₀ 10 + log₁₀ 95) | 0.3358 |
| The same values in SI units | 5.28 mmol/L and 60 pmol/L | HOMA-IR 2.35 (identical) |
| Comparison with the Bruneck threshold | 2.35 versus 2.77 | within the threshold |
The calculation in mmol/L gives exactly the same HOMA-IR and the same HOMA-β, because the constants of the two formulas differ only by the conversion factor.
How to read the values (and why there is no single threshold)
This is the most delicate point of the tool. There is no universal HOMA-IR threshold value: it changes with the population studied, with age, with sex and above all with the method the laboratory uses to measure insulin, which is not standardised. For this reason the calculator does not assign labels such as “normal” or “pathological”, but shows your value alongside two thresholds taken from published studies, each with its source:
| Reference | Value | Where it comes from |
|---|---|---|
| HOMA-IR — Bruneck study | 2.77 | lower limit of the top quintile among non-obese adults without metabolic disorders, population of Bruneck (Brunico, Bolzano); Bonora, Diabetes 1998 |
| HOMA-IR — EPIRCE study | 3.46 | 90th percentile of the general Spanish adult population; Gayoso-Diz, BMC Endocrine Disorders 2013 |
| QUICKI | 0.357 | lower limit of the 95% confidence interval in healthy subjects; Hrebíček, JCEM 2002 |
Being above one of these thresholds is not a diagnosis of insulin resistance, just as being below does not rule it out: they are population reference values, created for epidemiological research. The authors of QUICKI themselves write that the normal range should be established by each laboratory with its own control group, precisely because of the differences between insulin assays. HOMA-β, by contrast, is read as a percentage of a reference beta-cell function, and should always be interpreted together with glucose: a high value with normal glucose indicates a pancreas that is compensating by working harder.
When this calculation is not enough
This is an informational tool. For it to make sense you need glucose and insulin from the same blood draw taken while fasting (usually 8-12 hours): values taken at different times, or after a meal, give a meaningless result. The model was designed to compare groups of people, not to follow an individual patient over time, and the authors pointed out from the original publication that precision for a single individual is limited. There is also an updated version, HOMA2, which can only be calculated with the University of Oxford's software: the two results do not coincide.
A medical assessment is needed in any case if your fasting glucose is abnormal, if you are taking medications that affect glucose or insulin, during pregnancy, in the presence of polycystic ovary syndrome or fatty liver disease, and whenever the result worries you. Interpretation is up to your doctor, the only one who can read these numbers within your medical history. No value calculated on a web page is a reason to start, change or stop a treatment.
Frequently asked questions
How is the HOMA index calculated?
Multiply fasting glucose by fasting insulin from the same blood draw and divide by 405 if glucose is in mg/dL, or by 22.5 if it is in mmol/L, with insulin in µU/mL. With glucose 95 mg/dL and insulin 10 µU/mL, HOMA-IR is 95 × 10 / 405 = 2.35.
What is the normal value of the HOMA index?
There is no threshold valid for everyone: it depends on the population, age, sex and the laboratory's insulin assay, which is not standardised. Among published references, the Bruneck population study used 2.77 as the limit above which to consider insulin resistance, while in the Spanish adult population of the EPIRCE study the 90th percentile is 3.46. Exceeding a threshold is not a diagnosis.
What is HOMA-β and how does it differ from HOMA-IR?
HOMA-IR estimates how much the body resists the action of insulin, whereas HOMA-β estimates how much insulin the pancreatic beta cells are able to produce, expressed as a percentage of a reference. It is calculated as 360 × insulin / (glucose in mg/dL − 63) and is not defined when fasting glucose is equal to or below 63 mg/dL.
Do you need to fast to calculate the HOMA index?
Yes, and it is the most important condition. The model describes the balance between glucose and insulin at rest, so both values must come from the same blood draw taken while fasting, usually after 8-12 hours. With values collected at different times or after a meal, the result has no clinical meaning.
Related tools: the body mass index (BMI) calculator, the carbohydrate calculator and the calorie calculator.
