HbA1c to Average Glucose Converter

What HbA1c and eAG are

HbA1c (glycated haemoglobin) shows the percentage of haemoglobin in red blood cells that has sugar attached. Because red cells live about three months, it reflects your average blood glucose over roughly the last 2–3 months.

Estimated average glucose (eAG) turns that percentage into the same units as a finger-prick or lab glucose reading. This calculator uses the formula from the ADAG study (Nathan et al., 2008), adopted by the American Diabetes Association:

eAG (mg/dL) = 28.7 × HbA1c (%) − 46.7. To get mmol/L, divide by 18.

Quick reference

• 5% ≈ 97 mg/dL (5.4 mmol/L)
• 6% ≈ 126 mg/dL (7.0 mmol/L)
• 7% ≈ 154 mg/dL (8.6 mmol/L)
• 8% ≈ 183 mg/dL (10.2 mmol/L)
• 9% ≈ 212 mg/dL (11.8 mmol/L)

Diagnostic ranges (ADA)

• Below 5.7%: normal.
• 5.7–6.4%: prediabetes.
• 6.5% or higher: diabetes range. A diagnosis normally needs a second abnormal test unless symptoms are clear.

If your report shows HbA1c in mmol/mol (IFCC units), convert to % with: % = mmol/mol × 0.0915 + 2.15 (for example 48 mmol/mol ≈ 6.5%).

When HbA1c can be misleading

• Anaemia, recent blood loss or transfusion, pregnancy, kidney failure and some haemoglobin variants can make HbA1c read too high or too low.
• eAG is an average. Two people with the same HbA1c can have very different day-to-day highs and lows; a glucose meter or continuous monitor shows those.

For people with diabetes, a common treatment target is below 7%, but the right target is set individually by your doctor.

Educational estimate only. Please discuss your result with your doctor.