Estimated average glucose (eAG) is a translation of your A1C percentage into the same mg/dL units your glucose meter shows. The formula, developed in the 2008 ADAG study, is eAG = 28.7 x A1C – 46.7. An A1C of 7.0%, for example, equals an eAG of roughly 154 mg/dL.
What eAG Means
A1C is the percentage of hemoglobin molecules in your red blood cells that have glucose attached. It reflects average blood sugar over the prior 2 to 3 months, but the percentage format is unfamiliar to most people. eAG exists to close that gap by restating the same information in the mg/dL units you see every day on a finger-stick meter or continuous glucose monitor.
The American Diabetes Association endorsed eAG as a companion number to A1C in 2008 after an international study of 507 adults and children correlated A1C with detailed CGM and finger-stick data. The regression line from that study is the equation labs and calculators use today.
The ADAG Formula
The formal equation from Nathan and colleagues is:
eAG (mg/dL) = 28.7 x A1C (%) – 46.7
For mmol/L users, the equivalent formula is eAG (mmol/L) = 1.59 x A1C (%) – 2.59. Every 1% rise in A1C shifts eAG by about 28 to 29 mg/dL. You can run any A1C through our A1C calculator to get the eAG instantly.
A1C to eAG Conversion Table
| A1C (%) | eAG (mg/dL) | eAG (mmol/L) | Category |
|---|---|---|---|
| 5.0 | 97 | 5.4 | Normal |
| 5.5 | 111 | 6.2 | Normal |
| 5.7 | 117 | 6.5 | Prediabetes threshold |
| 6.0 | 126 | 7.0 | Prediabetes |
| 6.4 | 137 | 7.6 | Prediabetes (upper) |
| 6.5 | 140 | 7.8 | Diabetes threshold |
| 7.0 | 154 | 8.6 | ADA general target |
| 7.5 | 169 | 9.4 | Above target |
| 8.0 | 183 | 10.2 | Above target |
| 8.5 | 197 | 11.0 | High |
| 9.0 | 212 | 11.8 | High |
| 10.0 | 240 | 13.4 | Very high |
| 11.0 | 269 | 14.9 | Very high |
| 12.0 | 298 | 16.5 | Very high |
Why eAG Is Often Higher Than Your Meter Average
If you test your blood sugar mostly before breakfast and before dinner, your meter average will probably be lower than your eAG. That is because meter testing skews toward the lowest glucose points of the day. eAG, derived from A1C, reflects glucose exposure across all 24 hours, including post-meal spikes and overnight periods you rarely measure.
A CGM gives a fairer comparison because it samples every few minutes. A CGM’s 90-day average (GMI, glucose management indicator) is typically within 5 to 10 mg/dL of eAG for most people, but small differences are expected and clinically acceptable.
When eAG Is Unreliable
Because eAG is derived from A1C, anything that distorts A1C also distorts eAG. Common issues include:
- Anemia and iron deficiency can falsely raise A1C.
- Recent blood loss or transfusion temporarily lowers A1C.
- Hemoglobin variants (HbS, HbC, HbE) common in people of African, Mediterranean, or Southeast Asian descent can interfere depending on the lab method.
- Pregnancy increases red-blood-cell turnover and lowers A1C relative to true glucose.
- Chronic kidney disease and hemodialysis alter red-blood-cell lifespan.
In these situations, CGM-derived time in range and GMI are more trustworthy than eAG. See our A1C levels guide for the full list of factors that distort A1C results.
How to Use eAG in Daily Life
eAG is useful because it speaks your meter’s language. When your doctor says “your A1C is 7.2%,” that may not mean much. When they add “that is an average of about 160 mg/dL,” you can compare it directly to the numbers on your screen every day.
Practical ways to use eAG:
- Set a daily benchmark. If your A1C target is 6.5%, aim for most pre-meal readings under 140 mg/dL and post-meal under 180 mg/dL.
- Spot pattern problems. If your meter average is 130 mg/dL but your eAG is 180, you are missing high readings between tests – usually after meals or overnight.
- Track progress. A drop in eAG from 170 to 154 mg/dL means real improvement and predicts a lower complication risk.
eAG vs GMI vs Time in Range
| Metric | Source | Reflects | Best for |
|---|---|---|---|
| A1C | Lab blood test | 2-3 month average | Standard diagnosis and targets |
| eAG | Formula from A1C | Same as A1C in mg/dL | Making A1C intuitive |
| GMI | 14+ days of CGM | CGM-based average | Between A1C tests |
| Time in Range | CGM minutes at 70-180 mg/dL | Stability and hypo risk | Reducing variability |
| Meter Average | Finger-stick log | Only tested moments | Spot checks |
Worked Examples
Example 1. Maria’s lab reports an A1C of 6.2%. Plugging into the formula: 28.7 x 6.2 – 46.7 = 131.2 mg/dL. Her daily goal might be pre-meal readings between 110 and 140 mg/dL.
Example 2. James’ A1C drops from 8.4% to 7.0% after six months of treatment. His eAG moved from about 195 to 154 mg/dL – a 41 mg/dL average drop and a meaningful reduction in long-term complication risk.
Example 3. Lin has an A1C of 6.8% (eAG 149 mg/dL) but her CGM shows a 14-day average of 175 mg/dL. The gap suggests iron-deficiency anemia may be falsely lowering her A1C. Her clinician should investigate.
The Bottom Line
eAG is simply your A1C restated in the same mg/dL numbers you already know. It makes lab results actionable by putting them on the same scale as your meter. Use the formula (eAG = 28.7 x A1C – 46.7) or our A1C chart to convert, and combine eAG with time in range and daily testing for the clearest picture of how you are doing.
