A1C ↔ Average Blood Glucose Converter
Convert between A1C percentage and estimated average blood glucose (eAG). Based on the ADAG formula endorsed by the American Diabetes Association.
This calculator is for educational purposes only. Always consult your healthcare provider to interpret your actual test results.
An A1C calculator converts your A1C percentage into estimated average glucose (eAG) using the validated ADAG formula: eAG (mg/dL) = 28.7 × A1C − 46.7. An A1C of 7.0% equals an average glucose of about 154 mg/dL. The conversion makes lab results easier to compare with your daily meter readings.
The Conversion Formulas
| Direction | Formula |
|---|---|
| A1C → eAG (mg/dL) | eAG = 28.7 × A1C − 46.7 |
| A1C → eAG (mmol/L) | eAG = 1.59 × A1C − 2.59 |
| eAG (mg/dL) → A1C | A1C = (eAG + 46.7) ÷ 28.7 |
| eAG (mmol/L) → eAG (mg/dL) | mg/dL = mmol/L × 18.018 |
The formula comes from the A1C-Derived Average Glucose (ADAG) study, which used continuous glucose monitoring across 507 participants to validate the linear relationship.
Worked Examples
Example 1: A1C of 5.4%
eAG = 28.7 × 5.4 − 46.7 = 154.98 − 46.7 = 108 mg/dL (6.0 mmol/L). This is in the normal range — typical of someone without prediabetes.
Example 2: A1C of 6.0%
eAG = 28.7 × 6.0 − 46.7 = 172.2 − 46.7 = 126 mg/dL (7.0 mmol/L). Mid-prediabetes range.
Example 3: A1C of 7.5%
eAG = 28.7 × 7.5 − 46.7 = 215.25 − 46.7 = 168 mg/dL (9.4 mmol/L). Above the standard adult diabetes goal of less than 7.0%.
Example 4: Reverse — average glucose of 140 mg/dL
A1C = (140 + 46.7) ÷ 28.7 = 186.7 ÷ 28.7 = 6.5%. This is the diagnostic threshold for diabetes.
Full A1C to eAG Conversion Table
| A1C (%) | eAG (mg/dL) | eAG (mmol/L) | Category |
|---|---|---|---|
| 4.0 | 68 | 3.8 | Below normal range |
| 4.5 | 82 | 4.6 | Normal |
| 5.0 | 97 | 5.4 | Normal |
| 5.1 | 100 | 5.5 | Normal |
| 5.2 | 103 | 5.7 | Normal |
| 5.3 | 105 | 5.9 | Normal |
| 5.4 | 108 | 6.0 | Normal |
| 5.5 | 111 | 6.2 | Normal |
| 5.6 | 114 | 6.3 | Normal |
| 5.7 | 117 | 6.5 | Prediabetes |
| 5.8 | 120 | 6.7 | Prediabetes |
| 5.9 | 123 | 6.8 | Prediabetes |
| 6.0 | 126 | 7.0 | Prediabetes |
| 6.1 | 128 | 7.1 | Prediabetes |
| 6.2 | 131 | 7.3 | Prediabetes |
| 6.3 | 134 | 7.4 | Prediabetes |
| 6.4 | 137 | 7.6 | Prediabetes |
| 6.5 | 140 | 7.8 | Diabetes |
| 6.6 | 143 | 7.9 | Diabetes |
| 6.7 | 146 | 8.1 | Diabetes |
| 6.8 | 148 | 8.2 | Diabetes |
| 6.9 | 151 | 8.4 | Diabetes |
| 7.0 | 154 | 8.6 | Diabetes (target) |
| 7.5 | 168 | 9.4 | Diabetes (above target) |
| 8.0 | 183 | 10.1 | Diabetes (poor control) |
| 8.5 | 197 | 10.9 | Diabetes |
| 9.0 | 212 | 11.8 | Diabetes |
| 9.5 | 226 | 12.6 | Diabetes |
| 10.0 | 240 | 13.4 | Diabetes (very poor control) |
| 11.0 | 269 | 14.9 | Diabetes |
| 12.0 | 298 | 16.5 | Diabetes |
| 13.0 | 326 | 18.1 | Diabetes |
| 14.0 | 355 | 19.7 | Diabetes |
For more on what each percentage means clinically, see our A1C chart.
Why eAG and Meter Readings May Differ
A1C and the average from your home meter often differ by 0.3-0.5%. Reasons include:
- Sampling bias — meter checks happen at specific times (often before meals); A1C captures every moment.
- Red blood cell turnover — anemia, sickle cell trait, pregnancy.
- Glucose variability — two people with identical eAG can have very different ranges.
- Recent control changes — A1C lags by weeks.
How to Use the Calculator in Practice
- Plug your latest A1C into the formula or look it up in the table.
- Compare the eAG to your meter or CGM average from the same period.
- If the numbers diverge by more than 0.5% A1C equivalent, ask your doctor whether a non-glycemic factor might be at play.
- Use the eAG for goal-setting — most adults with diabetes target less than 154 mg/dL average (A1C under 7.0%).
Limits of the eAG Estimate
eAG is an estimate, not a direct measurement. The ADAG study found 95% confidence intervals of roughly ±15-20 mg/dL around the calculated value. Two people with the same A1C can have different glucose patterns — one stable, one with big swings. That is why time-in-range from a CGM is becoming a complementary measure to A1C, alongside our overview of A1C levels.
The Bottom Line
The A1C calculator converts a percentage into the mg/dL units you see on a glucose meter using eAG = 28.7 × A1C − 46.7. An A1C of 5.7% equals about 117 mg/dL average; 6.5% equals 140 mg/dL; 7.0% equals 154 mg/dL. The eAG is a useful translation but does not replace daily monitoring — pair it with meter or CGM data for the full picture.
