A1C Calculator
Convert between A1C percentage and estimated average glucose (eAG) in mg/dL and mmol/L.
How it works
eAG(mg/dL) = 28.7 × A1C − 46.7 · A1C = (eAG + 46.7) ÷ 28.7
A1C reflects your average blood sugar over roughly the past three months as the percentage of hemoglobin coated with glucose. The ADAG study gave a straight-line link between A1C and estimated average glucose (eAG), so you can read either in the other’s units. Divide mg/dL by 18 for mmol/L.
Worked example
An A1C of 7% converts to an estimated average glucose of 28.7 × 7 − 46.7 = 154 mg/dL, about 8.6 mmol/L.
Frequently asked questions
What A1C is normal?
General reference points are below 5.7% normal, 5.7–6.4% prediabetes, and 6.5% or higher in the diabetes range — but only a clinician can interpret your result alongside the full picture.
Why doesn’t my meter match my A1C?
A meter is a single moment; A1C is a three-month average. eAG bridges them, but daily readings still bounce around the average — and some conditions skew A1C itself.
Is eAG the same as a lab glucose test?
No — it’s a statistical estimate from A1C, not a measured value. Treat it as a translation aid, and rely on lab work for decisions.
Related calculators
General educational estimate, not medical advice. Talk to a doctor for anything about your health.