Free Estimated Average Glucose Calculator
Enter your HbA1c or blood glucose level to calculate your estimated average glucose
HbA1c to eAG: Understanding Your Average Blood Sugar
The Free Estimated Average Glucose Calculator (also known as an HbA1c to eAG calculator, Blood Sugar Average Calculator, or eAG to HbA1c converter) provides a quick conversion between your glycated hemoglobin (HbA1c) value and your estimated average glucose (eAG). This eAG reflects the typical blood sugar concentration over the preceding three months. Whether you need an A1c to average blood sugar conversion or want to work in reverse, this tool offers a reliable reference.
What Is HbA1c?
HbA1c, short for glycated hemoglobin (also called hemoglobin A1c), is formed when glucose molecules in the bloodstream bind to hemoglobin, the iron‑containing protein that transports oxygen inside red blood cells. Higher blood glucose levels increase the likelihood of glucose attaching to hemoglobin, producing HbA1c. Because red blood cells circulate for about 120 days, the HbA1c percentage provides an integrated view of average blood sugar over the previous two to three months. Clinicians use HbA1c measurements to evaluate insulin function, monitor diabetes management, and assess whether dietary and treatment plans are effective. Chronic insulin deficiency or resistance leads to diabetes mellitus, a condition that can be managed with insulin therapy or oral medications.
What Is Estimated Average Glucose (eAG)?
Estimated average glucose (eAG) — sometimes called estimated mean glucose or average glucose level — represents the mean blood glucose concentration over the same three‑month window captured by HbA1c. The conversion produces values in milligrams per deciliter (mg/dL) or millimoles per liter (mmol/L). The three‑month timeframe is chosen because most red blood cells survive for about 120 days, but because cells are continuously created and removed, a three‑month interval ensures that the majority of measured cells were present throughout the period of interest.
Normal Blood Sugar Ranges for HbA1c and eAG
Individuals Without Diabetes
- Normal: HbA1c < 5.7% → eAG < 139.85 mg/dL (< 7.77 mmol/L).
- Prediabetes: HbA1c between 5.7% and 6.5% (this category indicates higher‑than‑normal risk; no single eAG threshold is universally assigned).
- Diabetes diagnostic threshold: HbA1c ≥ 6.5% → eAG ≥ 139.85 mg/dL (≥ 7.77 mmol/L).
Individuals With Diabetes
Target A1c values depend on age and overall health:
| Group | Recommended HbA1c |
|---|---|
| Pregnant women with diabetes | < 6.0% |
| General population (excellent control) | < 6.5% |
| Children and adolescents | < 6.5% (with caution about hypoglycemia) |
| General population (recommended) | < 7.0% |
| Adults over 80 or with severe comorbidities | < 8.0% |
An A1c ≥ 7.0% is generally considered too high for the general population, and values ≥ 9.0% indicate a dangerously elevated level that requires immediate medical attention.
HbA1c to eAG Conversion Reference
The table below shows typical HbA1c values alongside their corresponding eAG levels. The figures in parentheses represent the commonly observed range around the estimated mean.
| HbA1c (%) | eAG (mg/dL) | eAG (mmol/L) |
|---|---|---|
| 5 | 97 (76–120) | 5.4 (4.2–6.7) |
| 6 | 126 (100–152) | 7.0 (5.5–8.5) |
| 7 | 154 (123–185) | 8.6 (6.8–10.3) |
| 8 | 183 (147–217) | 10.2 (8.1–12.1) |
| 9 | 212 (170–249) | 11.8 (9.4–13.9) |
| 10 | 240 (193–282) | 13.4 (10.7–15.7) |
| 11 | 269 (217–314) | 14.9 (12.0–17.5) |
| 12 | 298 (240–347) | 16.5 (13.3–19.3) |
| 13 | 326 (260–380) | 18.1 (15–21) |
| 14 | 355 (290–410) | 19.7 (16–23) |
| 15 | 384 (310–440) | 21.3 (17–25) |
How to Perform the Conversion
The standard formula for converting HbA1c (in %) to eAG (in mg/dL) is:
For example, an HbA1c of 7.0% gives:
To express the result in mmol/L, divide the mg/dL value by 18.015. The formula is derived from the Diabetes Control and Complications Trial (DCCT) and is widely accepted in clinical practice.
Important Disclaimer
This free estimated average glucose calculator is provided for informational and educational purposes only. It is not a substitute for professional medical advice, diagnosis, or treatment. Always consult a qualified healthcare provider for interpretation of your blood glucose levels and for personalized medical guidance.
FAQ
1. How do I calculate my estimated average glucose from my HbA1c?
Use the formula: eAG (mg/dL) = (28.7 × HbA1c%) - 46.7. For example, an HbA1c of 7% yields an eAG of 154.2 mg/dL. The calculator can do this for you instantly.
2. What is a normal HbA1c level for a person without diabetes?
An HbA1c below 5.7% is considered normal. Levels between 5.7% and 6.5% indicate prediabetes, and an HbA1c of 6.5% or higher suggests diabetes.
3. Why does the estimated average glucose reflect the past three months?
The estimation is based on HbA1c, which measures glycated hemoglobin in red blood cells. Since red blood cells live about 120 days (roughly 4 months) but are continuously replaced, a 3-month window provides a reliable average blood sugar level.
4. What are the target A1c levels for people with diabetes?
For the general population, below 7% is recommended. Excellent control is below 6.5%, while older adults (over 80) or those with severe health issues may aim for below 8%. Pregnant women with diabetes should target below 6%.
How to Use
- Select your calculation direction - convert HbA1c to eAG or eAG back to HbA1c.
- Enter your HbA1c percentage or average glucose value and choose your preferred unit (mg/dL or mmol/L).
- Click Calculate to see your estimated average glucose level and health status classification.