A1C to Average Glucose Calculator
Convert haemoglobin A1C to estimated average glucose (eAG) in both mg/dL and mmol/L, and convert in the reverse direction, using the ADAG study regression.
Formula & Reference
| Variable | Symbol | Formula | Units |
|---|---|---|---|
| A1C to Average Glucose Calculator | — | eAG (mg/dL) = 28.7 × A1C − 46.7 | mg/dL |
Step-by-Step Examples
A1C of 7.0%.
- eAG = 28.7 × 7.0 − 46.7
- eAG = 200.9 − 46.7 = 154 mg/dL
- In mmol/L: 154 / 18 = 8.6
A1C of 6.0%.
- eAG = 28.7 × 6.0 − 46.7
- eAG = 172.2 − 46.7 = 126 mg/dL
- Falls in the prediabetes band
Meter average of 183 mg/dL over three months.
- A1C = (183 + 46.7) / 28.7
- A1C = 229.7 / 28.7 = 8.0%
- Above the commonly cited 7% target
Real-World Applications
Common Mistakes to Avoid
The ADAG regression describes a population average. Individual red cell turnover rates cause meaningful scatter around the line, so a mismatch is not necessarily a measurement error.
Anaemia, haemoglobinopathies, recent transfusion, pregnancy, and chronic kidney disease all alter red cell lifespan and can make A1C misleading. Fructosamine or continuous glucose monitoring may be used instead.
A1C goals are individualised. Tighter targets suit some patients, while older adults or those with hypoglycaemia unawareness are often given deliberately looser ones.