About the HOMA-IR Calculator
The homeostasis model assessment (HOMA), published by Matthews and colleagues in Diabetologia in 1985, estimates insulin resistance (HOMA-IR) and pancreatic beta-cell function (HOMA-B, also written HOMA-%B) from a single pair of fasting glucose and fasting insulin measurements. It is widely used in research and metabolic clinics as a simple alternative to the euglycaemic clamp.
Enter fasting plasma glucose and fasting insulin in the units printed on the lab report — glucose in mg/dL or mmol/L and insulin in µU/mL (mU/L) or pmol/L. The calculator converts them, applies the original HOMA1 equations and also reports QUICKI, a related insulin-sensitivity index. By design, the model gives a HOMA-IR of 1.0 and a HOMA-B of 100% for normal-weight young adults in the reference population.
There is no single universal cut-off for insulin resistance: studies have used HOMA-IR thresholds from about 2.0 to 2.9 depending on population, ethnicity and insulin assay. HOMA is a population and research tool with limited precision for one person (the original paper reported coefficients of variation around 31%), it is not valid in people taking insulin, and it is not a diagnostic test for diabetes.
With the default inputs, the homa-ir is 2.35. Change any value above to recalculate instantly.
How to use the homa-ir calculator
- 1Take glucose and insulin from the same fasting blood sample (at least 8 hours without food).
- 2Enter fasting glucose and choose mg/dL or mmol/L.
- 3Enter fasting insulin and choose µU/mL or pmol/L.
- 4Read HOMA-IR (insulin resistance), HOMA-B (beta-cell function) and QUICKI.
- 5Compare results over time from the same lab rather than against a single universal cut-off.
Formula and method
These are the simple HOMA1 approximations from Matthews et al. (1985), with fasting glucose G in mmol/L and fasting insulin I in µU/mL. The constant 22.5 is the product of normal fasting insulin (5 µU/mL) and normal fasting glucose (4.5 mmol/L), so a reference adult scores exactly 1.0; HOMA-B is scaled so the same person scores 100%. With glucose in mg/dL the HOMA-IR equation becomes G × I ÷ 405.
Glucose in mg/dL is divided by 18 and insulin in pmol/L by 6 before applying the equations. QUICKI (quantitative insulin sensitivity check index) uses the same two values on a log scale; lower QUICKI means lower insulin sensitivity. The updated computer model HOMA2 gives somewhat different numbers and requires the official software.
- G
- Fasting plasma glucose (mmol/L)
- I
- Fasting plasma insulin (µU/mL)
- 22.5
- Normalising constant (4.5 mmol/L × 5 µU/mL)
Worked examples
Glucose 95 mg/dL, insulin 10 µU/mL
95 mg/dL ÷ 18 = 5.28 mmol/L. HOMA-IR = 5.28 × 10 ÷ 22.5 = 2.35, and HOMA-B = 20 × 10 ÷ (5.28 − 3.5) = 112.5%. QUICKI = 1 ÷ (log 10 + log 95) = 0.336.
SI units: 5.5 mmol/L and 72 pmol/L
72 pmol/L ÷ 6 = 12 µU/mL. HOMA-IR = 5.5 × 12 ÷ 22.5 = 2.93 and HOMA-B = 20 × 12 ÷ (5.5 − 3.5) = 120%.
High fasting glucose and insulin
126 mg/dL is 7.0 mmol/L. HOMA-IR = 7 × 25 ÷ 22.5 = 7.78, far above the reference of 1.0, and HOMA-B = 20 × 25 ÷ 3.5 = 142.9%. A glucose this high is itself in the diabetes range.
Frequently asked questions
What is a normal HOMA-IR?+
The model defines 1.0 as the value for normal-weight young adults in its reference group. Many studies treat values below about 2.0 as normal, but cut-offs for insulin resistance range from roughly 2.0 to 2.9 depending on population and insulin assay.
What does HOMA-B mean?+
HOMA-B (or HOMA-%B) estimates pancreatic beta-cell function as a percentage of the reference population, which scores 100%. High insulin resistance often comes with a high HOMA-B as the pancreas compensates; a low HOMA-B suggests insufficient insulin secretion.
How do I convert insulin from pmol/L to µU/mL?+
Divide pmol/L by 6 (1 µU/mL ≈ 6 pmol/L), which is the conversion used here. Some labs use 6.945; the difference changes HOMA-IR by about 14%, so use the same convention when comparing results.
Can HOMA-IR be used for people on insulin?+
No. HOMA relies on the body’s own fasting insulin, so injected insulin makes the result meaningless. It is also unreliable in severe hyperglycaemia and should be calculated from a genuinely fasting sample.
What is the difference between HOMA1 and HOMA2?+
HOMA1 is the simple equation set from 1985 used here. HOMA2 is an updated computer model that accounts for renal glucose losses and gives slightly different values; it must be calculated with the official Oxford software.
For healthcare professionals and education only. This calculator implements a published formula or score but is not a diagnosis and does not replace clinical judgment. Verify inputs and results against the original source before using them in patient care.