A1C Calculator
Convert between A1C and estimated average glucose (eAG), with diabetes category.
Enter your hemoglobin A1C percentage
Enter your estimated average glucose
Estimated Average Glucose
Diabetes Category
The conversion is based on the ADAG study regression: eAG (mg/dL) = 28.7 × A1C − 46.7. Results are estimates and should be interpreted by a healthcare professional.
What A1C and eAG Mean
The hemoglobin A1C test (also called HbA1c or glycated hemoglobin) measures the percentage of hemoglobin proteins in your blood that are coated with sugar (glycated). Because red blood cells live for about three months, A1C reflects your average blood glucose over the previous 2-3 months rather than a single moment in time.
Estimated average glucose (eAG) translates the A1C percentage into the same units used for everyday glucose meters (mg/dL or mmol/L). This makes the result easier to relate to the daily self-monitored readings many people with diabetes already track. An A1C of 7%, for example, corresponds to an eAG of roughly 154 mg/dL (8.6 mmol/L).
The Conversion Formula (ADAG Study)
The relationship between A1C and average glucose comes from the A1c-Derived Average Glucose (ADAG) study, published in 2008, which used continuous glucose monitoring and frequent fingerstick testing across more than 500 participants to derive a linear regression between A1C and mean glucose.
eAG (mg/dL) = 28.7 × A1C − 46.7
eAG (mmol/L) = eAG(mg/dL) / 18.0182
A1C (%) = (eAG mg/dL + 46.7) / 28.7
A1C Diabetes Thresholds
The American Diabetes Association uses the following A1C ranges to classify glucose status. Diagnosis should always be confirmed by a clinician, often with a repeat test.
| Category | A1C Range |
|---|---|
| Normal | Below 5.7% |
| Prediabetes | 5.7% - 6.4% |
| Diabetes | 6.5% and above |
Note: This calculator provides estimates based on the ADAG study regression and is intended for educational purposes only. It is not a diagnostic tool and cannot replace laboratory testing or professional medical advice. Individual A1C-to-glucose relationships vary with factors such as anemia, hemoglobin variants, pregnancy, and red blood cell turnover. Always consult a qualified healthcare provider regarding diagnosis and management of diabetes.