This calculator computes HOMA-IR from fasting insulin and fasting glucose using the original homeostasis model assessment equation. It returns an index, not a diagnosis. HOMA-IR has no universal cut-off and is not standardized across assays, so the result is not a test of insulin resistance on its own.
What this calculator does
HOMA-IR is a model, not a measurement. It estimates how much fasting insulin is needed to hold fasting glucose at the level on the report. The original equation was described by Matthews and colleagues in 1985, and it remains the version most often cited when a report or a study names HOMA-IR.
The index is used in research and in some clinical settings as one part of a broader assessment. It is not a laboratory test with a universal reference range, and it is not a diagnosis. Laboratories that print it may use a different insulin assay or a different equation, so the number on the report is the one to follow.
The equation
The original HOMA-IR equation, with insulin in µIU/mL and glucose in mg/dL:
HOMA-IR = (fasting insulin × fasting glucose) / 405With glucose in mmol/L, the equivalent form is:
HOMA-IR = (fasting insulin × fasting glucose) / 22.5| Variable | Meaning |
|---|---|
| Fasting insulin | Insulin concentration in µIU/mL, measured after a fast. |
| Fasting glucose | Glucose concentration after the same fast, in mg/dL or mmol/L. |
| 405 | The constant in the original equation when glucose is in mg/dL. |
| 22.5 | The constant that gives the same index when glucose is in mmol/L. |
| HOMA-IR | The calculated index, with no unit. |
How to use it
- Confirm that both the insulin and the glucose were measured on fasting samples from the same draw or the same fasting episode.
- Enter insulin in µIU/mL. Some reports write mIU/L; for insulin, the numeric scale is the same.
- Enter glucose in the unit printed on the report and select that unit.
- Read the result as an index. It does not replace the report's values, comments, or a clinician's assessment.
What the result means, and what it does not
A higher HOMA-IR means the model estimates more insulin for the same fasting glucose. That can be consistent with insulin resistance, but the index is not specific and not standardized. A lower value means less insulin in the model, but it does not by itself prove that insulin sensitivity is normal.
The calculator does not assign a category, a cut-off, or a diagnosis. It does not tell you whether the result is normal, and it does not replace the report's comment. Insulin assays differ, fasting status matters, and a single value is weaker evidence than a pattern read with the rest of the results.
Limitations
- Fasting is required. The equation is built from fasting values. A non-fasting sample does not produce a valid HOMA-IR.
- Insulin assay differences. Insulin assays are not standardized across laboratories, so the same person can get different values on different assays.
- No universal cut-off. Studies and populations use different thresholds, and a value that is high in one context may not be high in another.
- A model, not a measurement. HOMA-IR estimates a relationship; it does not measure insulin resistance directly.
- One value is not a trend. A single result is weaker than repeated results from the same laboratory.
What this page is not
This calculator is a calculation from a published model. It is not a diagnosis of insulin resistance or of any condition, not a treatment recommendation, and not medical advice. It does not replace the values or comments on your report. Verify the inputs against the original report and discuss the result with a qualified professional.