# HOMA-IR calculator (fasting insulin and glucose)

> Doctano turns the lab reports you already have into one private, source-linked health timeline, with an AI that answers from your own results.

The original index from two fasting values, with the equation and its limits stated plainly.

This is the Markdown version of https://doctano.com/tools/homa-ir-calculator. The HTML page is the canonical version and carries the interactive calculator.

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:

```text
HOMA-IR = (fasting insulin × fasting glucose) / 405
```

With glucose in mmol/L, the equivalent form is:

```text
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. |

Source: [Matthews DR, Hosker JP, Rudenski AS, Naylor BA, Treacher DF, Turner RC. Homeostasis model assessment: insulin resistance and beta-cell function from fasting plasma glucose and insulin concentrations in man. Diabetologia. 1985;28(7):412-419.](https://pubmed.ncbi.nlm.nih.gov/3899825/)

## How to use it

1. Confirm that both the insulin and the glucose were measured on fasting samples from the same draw or the same fasting episode.
2. Enter insulin in µIU/mL. Some reports write mIU/L; for insulin, the numeric scale is the same.
3. Enter glucose in the unit printed on the report and select that unit.
4. 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.

## HOMA-IR calculator questions

**What is HOMA-IR?**

HOMA-IR is a calculated index derived from fasting insulin and fasting glucose. It is used as a model of how much insulin is needed to maintain a given glucose level. It is not a laboratory measurement and not a diagnosis.

**What equation does this calculator use?**

It uses the original homeostasis model assessment equation from Matthews and colleagues: fasting insulin in uIU/mL multiplied by fasting glucose in mg/dL, divided by 405. With glucose in mmol/L, the same index is insulin multiplied by glucose and divided by 22.5.

**Is there a normal HOMA-IR?**

There is no universal cut-off. Values differ between populations, assays, and studies, and insulin assays are not standardized across laboratories. This page does not print a range. Use the report's comment and a clinician's reading for your own result.

**Can HOMA-IR diagnose insulin resistance?**

No. HOMA-IR is a research and clinical model, not a standalone diagnostic test. Insulin resistance is assessed from the whole picture, including glucose results, history, and other findings. This calculator does not diagnose anything.

**Do I need to be fasting for HOMA-IR?**

Yes. The model is built from fasting insulin and fasting glucose. A non-fasting sample does not fit the equation, and the result would not be a HOMA-IR in the intended sense.

## Limits

**This is a calculation, not a diagnosis.** HOMA-IR has no universal cut-off and is not standardized across insulin assays. It does not tell you whether you have insulin resistance. Discuss the result with a qualified professional.

## Links

- [Homepage](https://doctano.com/)
- [Lab report tracker](https://doctano.com/lab-report-tracker)
- [All tools](https://doctano.com/tools/)
- [HOMA-IR](https://doctano.com/tests/homa-ir)
- [Fasting insulin](https://doctano.com/tests/fasting-insulin)
- [Fasting glucose](https://doctano.com/tests/fasting-glucose)
- [Diabetes panel](https://doctano.com/panels/diabetes-panel)
- [All guides](https://doctano.com/guides/)