How this calculator works
The ADAG study fitted a statistical relationship between laboratory HbA1c and average glucose. Its published mg/dL and mmol/L coefficients are independently rounded; this page preserves each equation exactly. This page limits HbA1c to 4-12%, avoiding extrapolation beyond the published table. The reverse operation is an estimate, not a measured HbA1c or a CGM glucose-management indicator. Anaemia, altered red-cell survival and some haemoglobin variants can affect interpretation. The result is an estimate for information only and is not medical advice.
Formula
eAG(mg/dL) = 28.7 x HbA1c(%) - 46.7. eAG(mmol/L) = 1.59 x HbA1c(%) - 2.59. Reverse: HbA1c = (eAG - intercept)/slope.
Worked example
HbA1c 7% gives 154.2 mg/dL or 8.54 mmol/L using the respective published equations. HbA1c 6% gives 125.5 mg/dL or 6.95 mmol/L.
Advertisement
Frequently asked questions
Is this a diagnosis of diabetes?
No. Diagnosis uses appropriate laboratory testing and clinical guidance, not a converted average alone.
Can one fingerstick reading estimate HbA1c?
No. The relationship concerns an average over time, not a single glucose result.
Why do the two unit equations differ slightly after conversion?
The original study rounded both regressions. This tool retains those published coefficients rather than silently replacing one.