This HOMA-IR calculator estimates insulin resistance from a fasting insulin and fasting glucose pair — the homeostatic model assessment used across metabolic research — with unit conversion built in.
HOMA-IR = (Fasting Insulin × Fasting Glucose) ÷ 405
The logic: in a fasting steady state, glucose is held by basal insulin; needing more insulin to hold the same glucose means the tissues are resisting it. The 405 (or 22.5 when glucose is in mmol/L) normalizes a healthy young reference to a HOMA-IR of ~1. Glucose units convert via our Blood Sugar Converter. Part of our Health Calculators collection.
Worked Example (Verified)
- Insulin 12 µU/mL, glucose 100 mg/dL (defaults): 12 × 100 ÷ 405 = 2.96 — above the commonly cited ~2.5 insulin-resistance threshold, the "normal glucose, expensive upkeep" picture HOMA-IR exists to catch
- Lean reference: insulin 5, glucose 85 → 1.05 — the model's anchor point made flesh
- The trap case: insulin 4 with glucose 200 gives 1.98 — a "fine" score produced by failing beta cells, not sensitivity; HOMA-IR is only interpretable while the pancreas can still compensate
- SI check: glucose 5.55 mmol/L (= 100 mg/dL) with insulin 12 → (12 × 5.55) ÷ 22.5 = 2.96 ✔ the two conventions agree
Companion Index & Context
- HOMA-β (beta-cell function) = (20 × insulin) ÷ (glucose in mmol/L − 3.5) — the model's other half, often reported alongside.
- QUICKI and the euglycemic clamp are the research alternatives; the clamp is the gold standard HOMA approximates.
- Fasting matters: a non-fasting pair invalidates the steady-state assumption completely.
- Trends beat snapshots: insulin assays vary between labs, so longitudinal comparisons ideally use the same lab.
Related Tools
- Blood Sugar Converter — mg/dL ↔ mmol/L
- A1C Calculator — the 3-month glucose average
- Health Calculators — the full collection
Frequently Asked Questions
How is HOMA-IR calculated?
(Fasting insulin in µU/mL × fasting glucose in mg/dL) ÷ 405 — or ÷ 22.5 with glucose in mmol/L. Insulin 12 and glucose 100 gives 2.96. Both samples must be fasting (typically 8–12 hours) for the model's steady-state assumption to hold.
What is a normal HOMA-IR?
The model is calibrated so ~1.0 is a healthy reference. Published "insulin resistance" cutoffs vary — roughly 2.0–2.5 in many adult studies, lower in some populations, higher in others — which is why results should be read as a band with clinical context, not a binary verdict.
Can HOMA-IR diagnose diabetes or insulin resistance?
No. Diabetes is diagnosed by glucose/A1C criteria; insulin resistance is a physiological state assessed clinically. HOMA-IR is a surrogate index used in research and screening conversations — a prompt for follow-up, not a diagnosis.
Why might HOMA-IR be misleading?
When beta cells can no longer mount insulin (advanced type 2 diabetes), low insulin with high glucose produces a deceptively mild score. It's also unreliable with insulin therapy, in acute illness, and when the sample isn't truly fasting. Assay differences between labs add noise to single readings.
What can improve insulin resistance?
The evidence-backed levers are unglamorous: weight loss where relevant, regular aerobic and resistance exercise, sleep adequacy, and reduced refined-carbohydrate load — with medications (e.g. metformin) a clinician's call. Retesting after a few months of change is how the index earns its keep.
Is this HOMA-IR calculator free?
Yes — free, instant, no sign-up. An educational index calculation, not medical advice.