HbA1c to Blood Glucose Converter
Convert HbA1c percentage to average blood glucose (mg/dL or mmol/L) and back.
Includes diabetes classification using ADA 2008 formula.
What Is HbA1c? HbA1c (glycated hemoglobin) measures the percentage of hemoglobin molecules in your blood that have glucose attached. Because red blood cells live about 90 days, HbA1c reflects your average blood sugar over the past 2–3 months — making it far more informative than a single fasting glucose test.
ADA 2008 Formula The American Diabetes Association (ADA) published the eAG (estimated Average Glucose) formula in 2008, derived from the ADAG clinical study:
Average Glucose (mg/dL) = (HbA1c × 28.7) − 46.7 Average Glucose (mmol/L) = (HbA1c × 1.594) − 2.594
Reverse Calculation HbA1c (%) = (Average Glucose mg/dL + 46.7) / 28.7
Diabetes Classification (ADA 2023)
- Normal: HbA1c below 5.7% (avg glucose below 117 mg/dL / 6.5 mmol/L)
- Pre-diabetes: HbA1c 5.7%–6.4% (avg glucose 117–137 mg/dL / 6.5–7.6 mmol/L)
- Diabetes: HbA1c 6.5% or higher (avg glucose 140+ mg/dL / 7.8+ mmol/L)
Treatment Targets For people already diagnosed with type 2 diabetes, the general ADA treatment target is HbA1c below 7.0% (avg glucose below 154 mg/dL / 8.6 mmol/L). Individual targets may vary.
HbA1c vs Fasting Glucose A single fasting glucose reading can vary day to day based on recent meals, stress, and illness. HbA1c provides a much longer-term picture. Both tests together give the most complete assessment.
Important Note HbA1c can be falsely low in people with certain anemias (sickle cell, iron deficiency) and falsely high in iron-deficiency anemia. Always discuss results with a healthcare provider.