Skip to content
Health Calculators › Metabolic Health
HOMA-IR Calculator
Estimate insulin resistance from fasting insulin and fasting glucose using the original Matthews et al. homeostatic model — with HOMA-%B (beta-cell function) and HOMA-%S (insulin sensitivity) included, and support for both US and international lab units.
What Is HOMA-IR?
HOMA-IR stands for Homeostatic Model Assessment of Insulin Resistance. It’s a mathematical estimate — derived from just two fasting blood values, insulin and glucose — of how well your body’s cells are responding to insulin. When cells become resistant to insulin’s signal, the pancreas compensates by producing more of it, which shows up as elevated fasting insulin even when glucose looks normal. HOMA-IR captures that relationship in a single number, without requiring the far more invasive and expensive gold-standard test (the hyperinsulinemic-euglycemic clamp).
The model was developed in 1985 by Matthews, Hosker, Rudenski, Naylor, Treacher, and Turner at Oxford, and it remains the most widely used insulin resistance estimate in both research and clinical screening today, precisely because it only needs a single fasting blood draw.
The HOMA-IR Formula
This calculator uses the original Matthews model formulas, converting inputs internally to a common unit basis so both US (mg/dL, μIU/mL) and international (mmol/L, pmol/L) lab reports work correctly:
HOMA-IR = (Fasting Insulin [μIU/mL] × Fasting Glucose [mmol/L]) ÷ 22.5
The model also produces two companion figures from the same two lab values, both included in this calculator’s results:
- HOMA-%B (beta-cell function): (20 × Fasting Insulin) ÷ (Fasting Glucose [mmol/L] − 3.5), expressed as a percentage of a healthy reference population’s average function.
- HOMA-%S (insulin sensitivity): 100 ÷ HOMA-IR, the inverse relationship — as resistance goes up, sensitivity goes down.
Most free HOMA-IR calculators online only return the IR score. Including %B and %S matters because they were part of the same original model and tell two different halves of the story: %B reflects how hard your pancreas is working to produce insulin, while %S reflects how effectively your body is using it.
How This Calculator Works
Enter your fasting insulin and fasting glucose values exactly as they appear on your lab report, and select the matching unit from each dropdown — μIU/mL or pmol/L for insulin, mg/dL or mmol/L for glucose. The calculator converts everything internally (pmol/L to μIU/mL by dividing by 6.945; mg/dL to mmol/L by dividing by 18.0182) before applying the formulas, so you never need to do unit conversion by hand or risk plugging the wrong figure into the wrong formula.
Understanding Your HOMA-IR Score
There is no single universally agreed diagnostic cutoff for HOMA-IR — thresholds vary somewhat by population, lab assay, and study — but the ranges below reflect commonly cited general benchmarks used in screening and research contexts:
| HOMA-IR Range | General Interpretation |
|---|---|
| Below 1.0 | Optimal insulin sensitivity |
| 1.0 – 1.9 | Within a normal, sensitive range for most healthy adults |
| 2.0 – 2.9 | Early signs of reduced insulin sensitivity in many studies |
| 3.0 and above | Often associated with insulin resistance in research literature |
These bands are general reference points, not diagnostic thresholds. Some research studies use a cutoff as low as 2.5, others closer to 3.0, and pediatric or pregnancy-specific reference ranges differ further still. Only a healthcare provider, working with your full clinical picture, can properly interpret what your specific number means for you.
Worked Examples
| Fasting Insulin | Fasting Glucose | HOMA-IR | General Read |
|---|---|---|---|
| 5 μIU/mL | 85 mg/dL | 1.05 | Sensitive range |
| 10 μIU/mL | 90 mg/dL | 2.22 | Borderline / reduced sensitivity range |
| 18 μIU/mL | 100 mg/dL | 4.44 | Resistant range |
| 25 μIU/mL | 110 mg/dL | 6.79 | Strongly resistant range |
What Can Affect Your HOMA-IR Result
- Fasting compliance. HOMA-IR requires a true fasting sample — typically 8–12 hours without food. Eating beforehand invalidates the calculation entirely, since both insulin and glucose rise sharply after a meal.
- Time of day and circadian rhythm. Fasting insulin can vary somewhat depending on when in the morning the blood draw was taken.
- Lab assay differences. Different labs use different insulin assay methods, which can produce meaningfully different results for the same actual insulin level — this is a well-documented limitation of HOMA-IR as a standardized metric.
- Acute illness or stress. Short-term illness, poor sleep the night before, or significant stress can temporarily elevate fasting glucose or insulin.
- Medications. Corticosteroids, some hormonal medications, and diabetes medications can all directly influence fasting glucose or insulin readings.
HOMA-%B and HOMA-%S: The Other Half of the Model
HOMA-IR gets most of the attention, but the original model was built to estimate two things simultaneously: how much insulin your pancreas is producing (%B) and how sensitive your tissues are to it (%S). A person can have a normal HOMA-IR while still showing early compensatory changes in %B, which is one reason researchers often look at both figures together rather than relying on HOMA-IR alone. Both %B and %S are indexed to 100%, representing the average of a healthy young reference population from the original 1985 study — values notably above or below 100% suggest a deviation from that reference, though, like HOMA-IR itself, this is a research-oriented estimate rather than a diagnostic figure.
Where HOMA-IR Is Used
🔬 Research & Clinical Studies
HOMA-IR is one of the most frequently used insulin resistance measures in epidemiological and clinical research, largely because it only requires a single fasting blood draw rather than the multi-hour clamp procedure.
🩺 Metabolic Syndrome & Prediabetes Screening
Clinicians sometimes use HOMA-IR alongside fasting glucose, waist circumference, blood pressure, and lipid panels as part of a broader metabolic syndrome risk picture — never as a single standalone diagnostic test.
🩺 PCOS Evaluation
Insulin resistance is common in polycystic ovary syndrome, and HOMA-IR is frequently used in PCOS research and clinical evaluation as one supporting data point alongside hormonal and clinical assessment.
⚖️ Weight Management & Lifestyle Monitoring
Some individuals track HOMA-IR periodically alongside diet and exercise changes as one indicator of metabolic trend over time — though a single reading is far less informative than a trend across multiple properly-fasted tests.
Limitations of HOMA-IR
HOMA-IR is a useful, low-cost estimate — but it is not the gold standard. The hyperinsulinemic-euglycemic clamp technique, which directly measures how much glucose must be infused to maintain stable blood sugar while insulin is held at a fixed elevated level, remains the true reference method for measuring insulin sensitivity, but it’s expensive, time-consuming, and largely confined to research settings. HOMA-IR approximates that gold-standard measurement reasonably well at a population level, but its accuracy for any single individual can be affected by assay variability, non-standardized fasting conditions, and normal day-to-day biological fluctuation. It should always be interpreted as one data point within a broader clinical picture, not a stand-alone verdict.
Common Mistakes to Avoid
- Using a non-fasting blood sample. Any calculation performed on post-meal insulin and glucose values is not a valid HOMA-IR result.
- Mismatching units. Entering an mg/dL glucose value while the calculator (or a manual formula) expects mmol/L produces a wildly incorrect score — always confirm which unit your lab report uses.
- Treating a single score as diagnostic. One HOMA-IR reading is a snapshot, not a diagnosis — trends over time and a full clinical evaluation matter far more than any single number.
- Ignoring lab-to-lab assay variability. Comparing HOMA-IR scores from two different labs (which may use different insulin assay methods) can be misleading without accounting for that variability.
Frequently Asked Questions
Many studies use a value below roughly 1.0–1.9 as within a normal, sensitive range for healthy adults, though exact cutoffs vary by population and lab assay. This is a general reference, not a fixed diagnostic threshold.
You need two values from a true fasting blood draw: fasting insulin and fasting glucose, both typically reported on a standard fasting metabolic lab panel.
No. HOMA-IR is a screening and research estimate only. Diagnosis requires clinical evaluation by a licensed healthcare professional, who will consider your full medical history alongside any lab results.
HOMA-%B estimates pancreatic beta-cell function (how much insulin your body is producing), while HOMA-%S estimates insulin sensitivity (how effectively your body is using that insulin) — both derived from the same original 1985 model as HOMA-IR.
Eating causes both insulin and glucose to rise sharply, which would invalidate the calculation. HOMA-IR specifically measures the fasting baseline relationship between the two.
Yes — select the unit that matches your lab report from the dropdown, and the calculator converts internally before applying the HOMA formulas.
Different labs sometimes use different insulin assay methods, which can produce meaningfully different readings for the same actual insulin level — a well-documented limitation of HOMA-IR as a standardized measure.
No — the hyperinsulinemic-euglycemic clamp remains the gold-standard direct measurement of insulin sensitivity. HOMA-IR is a validated, much simpler estimate that correlates reasonably well with the clamp at a population level, but is less precise for any single individual.
Yes, it’s commonly used as one supporting data point in PCOS-related research and clinical evaluation, though it should always be interpreted alongside other clinical and hormonal findings.
Yes — it’s completely free, with no login and no limit on how many times you can use it.
Final Thoughts
HOMA-IR distills a complex physiological relationship — how well insulin and glucose are working together — into a single number from one fasting blood draw. This calculator adds the two companion figures the original model was built to produce (%B and %S), supports both US and international lab units, and presents the result on a clear visual scale — but it remains, as it always has been, a screening estimate. Treat your result as one useful data point to bring to a conversation with a healthcare professional, not a diagnosis in itself.
