Estimated Average Glucose Calculator
Convert an A1C result into an estimated average glucose value in mg/dL or mmol/L.
How is this calculated?
Formula (mg/dL): eAG = (28.7 × A1C) - 46.7
Formula (mmol/L): eAG = (1.59 × A1C) - 2.59
Based on the ADAG (A1c-Derived Average Glucose) study.
| Normal | A1C < 5.7% |
| Prediabetes | A1C 5.7% – 6.4% |
| Diabetes | A1C ≥ 6.5% |
What Is an Estimated Average Glucose Calculator?
An estimated average glucose (eAG) calculator converts your A1C percentage into an average blood sugar level over the past two to three months. The result is expressed in mg/dL (milligrams per deciliter) or mmol/L (millimoles per liter), matching the units you see on a daily glucose meter. This conversion helps bridge the gap between lab-based A1C measurements and day-to-day blood glucose monitoring.
How the Conversion Works
The calculation follows the ADAG (A1c-Derived Average Glucose) study formula, which is the standard used by clinicians and diabetes organizations worldwide.
Formula for mg/dL: eAG = 28.7 × A1C − 46.7
Formula for mmol/L: eAG = 1.59 × A1C − 2.59
For example, an A1C of 7% converts to an eAG of approximately 154 mg/dL (8.6 mmol/L). The formula assumes a linear relationship between A1C and average glucose, which holds true for most individuals without hemoglobin variants or conditions affecting red blood cell turnover.
How to Use the Calculator
- Enter your A1C percentage (e.g., 6.5, 7.2, 8.0).
- Select your preferred output unit: mg/dL or mmol/L.
- Click calculate to see your estimated average glucose value.
The tool accepts A1C values within the clinically relevant range. Results are rounded to one decimal place for practical use.
Understanding Your Results
The eAG value represents an average, not a target. It reflects your mean blood glucose over approximately 90 days, weighted more heavily toward the most recent 30 days. Use it as a benchmark to assess overall glucose control, not as a substitute for daily monitoring.
Typical eAG ranges by A1C:
| A1C (%) | eAG (mg/dL) | eAG (mmol/L) |
|---|---|---|
| 5.7 | 117 | 6.5 |
| 6.0 | 126 | 7.0 |
| 6.5 | 140 | 7.8 |
| 7.0 | 154 | 8.6 |
| 8.0 | 183 | 10.2 |
| 9.0 | 212 | 11.8 |
| 10.0 | 240 | 13.4 |
Common Misconceptions
- eAG is not the same as your daily average. Your daily meter average may differ due to timing, missed readings, or meter accuracy. The eAG is a lab-derived estimate, not a direct calculation from your meter log.
- A single A1C value has limitations. Conditions like anemia, kidney disease, or recent blood transfusions can affect A1C accuracy. The eAG formula assumes normal red blood cell lifespan.
- eAG does not show variability. Two people with the same A1C can have very different glucose patterns. One may have stable levels, while the other experiences frequent highs and lows.
Practical Use Cases
- Setting glucose targets: Use eAG to translate A1C goals into everyday glucose numbers you can track on your meter.
- Discussing results with your doctor: eAG provides a common language for comparing lab results with self-monitoring data during appointments.
- Monitoring treatment changes: After adjusting medication, diet, or exercise, track how your eAG changes over successive A1C tests.
- Patient education: For people newly diagnosed with diabetes, eAG makes A1C results more tangible and actionable.
Frequently Asked Questions
Is eAG the same as my average blood sugar from my glucose meter?
Not exactly. Your meter calculates an average from the readings you take, which may not capture all glucose fluctuations throughout the day. eAG is derived from A1C, which reflects glucose exposure over weeks. The two numbers often align but can differ due to gaps in monitoring or meter calibration differences.
Can I use eAG to adjust my insulin or medication?
No. eAG is a retrospective average and should not guide immediate treatment decisions. Always use real-time glucose readings from your meter or CGM for dosing adjustments. Discuss eAG trends with your healthcare provider to inform long-term treatment plans.
Why does my eAG seem higher than my meter average?
This is common. Meters may underreport glucose levels if you test mostly during fasting or pre-meal periods. A1C captures post-meal spikes and overnight glucose that your meter might miss. The eAG formula also assumes a specific relationship that may not perfectly match your physiology.
Does the calculator work for children or pregnant women?
The ADAG formula was validated primarily in adults with type 1 and type 2 diabetes. For children and pregnant individuals, the relationship between A1C and average glucose may differ. Use the calculator as a general reference, but rely on clinical guidance for interpretation in these populations.
What if my A1C is below 4% or above 14%?
Values outside the typical clinical range may produce unreliable eAG estimates. The formula is most accurate for A1C values between 4% and 14%. If your result falls outside this range, consult your doctor for proper evaluation.