A1C / eAG Calculator
Convert between clinical HbA1c percentage and Estimated Average Glucose (eAG) using the official ADA formula.
Conversion Details
Enter a value to see your converted A1C / eAG result
Scientific Formula & Calculation Methodology (ADAG (A1C-Derived Average Glucose) Linear Regression Formula (Nathan et al., 2008))
eAG (mg/dL) = 28.7 × HbA1c (%) - 46.7. For SI units (mmol/L): eAG (mmol/L) = [28.7 × HbA1c - 46.7] ÷ 18.01559. Conversely: HbA1c (%) = [eAG (mg/dL) + 46.7] ÷ 28.7. The clinical consensus was established by the landmark A1C-Derived Average Glucose study endorsed by the American Diabetes Association (ADA), European Association for the Study of Diabetes (EASD), and International Diabetes Federation (IDF).
Important Clinical Limitations of HbA1c & Estimated Average Glucose (eAG) Calculator
- HbA1c reflects red blood cell (erythrocyte) turnover over their standard ~120-day lifespan. Conditions altering erythrocyte survival (such as hemolytic anemia, sickle cell trait, chronic kidney disease on erythropoietin, or recent blood transfusion) cause spuriously inaccurate A1C results.
- eAG represents a weighted mathematical average where the preceding 30 days account for roughly 50% of the glycation value, and days 90–120 contribute only 10%.
- A single eAG calculation cannot detect rapid acute glycemic volatility, nocturnal hypoglycemia, or severe postprandial spikes that a continuous glucose monitor (CGM) or fingerstick log would reveal.
- Pregnancy accelerates erythrocyte turnover, meaning lower clinical A1C targets apply during gestation.
Peer-Reviewed Literature & Recognized Medical Sources
Quick Guide Summary: Essential HbA1c & eAG Facts
< 5.7% (eAG < 117 mg/dL). Indicates healthy long-term glucose regulation.
5.7% to 6.4% (eAG 117–137 mg/dL). High risk for progression to type 2 diabetes.
≥ 6.5% (eAG ≥ 140 mg/dL) on two separate clinical evaluations confirms diabetes.
For non-pregnant adults with diabetes, the ADA generally recommends an A1C target < 7.0% (eAG < 154 mg/dL).
Clinical A1C to Estimated Average Glucose (eAG) Matrix
The table below illustrates the linear translation between laboratory HbA1c percentages and daily home blood glucose meter values according to the ADAG formula:
| HbA1c (%) | eAG (mg/dL) | eAG (mmol/L) | ADA Clinical Classification |
|---|---|---|---|
| 5.0% | 97 mg/dL | 5.4 mmol/L | Normal Healthy Baseline |
| 5.5% | 111 mg/dL | 6.2 mmol/L | Normal Healthy Baseline |
| 5.7% | 117 mg/dL | 6.5 mmol/L | Prediabetes Threshold |
| 6.0% | 126 mg/dL | 7.0 mmol/L | Prediabetes Range |
| 6.5% | 140 mg/dL | 7.8 mmol/L | Diabetes Diagnostic Cutoff |
| 7.0% | 154 mg/dL | 8.6 mmol/L | Standard ADA Treatment Target |
| 8.0% | 183 mg/dL | 10.2 mmol/L | Elevated Glycemic Risk |
| 10.0% | 240 mg/dL | 13.3 mmol/L | Severe Hyperglycemia / Review Needed |
What Exactly is Glycated Hemoglobin (HbA1c)?
Hemoglobin is the iron-rich protein inside red blood cells responsible for transporting oxygen from your lungs to tissues across the body. When glucose circulates in the bloodstream, a fraction of it naturally binds chemically to hemoglobin without the aid of enzymes—a process called non-enzymatic glycation.
Because human red blood cells survive in circulation for approximately 110 to 120 days before being recycled by the spleen, the percentage of glycated hemoglobin provides an immutable 90 to 120 day rolling record of ambient glycemic exposure. Unlike a fasting fingerstick test, which fluctuates by minute based on anxiety or your last meal, HbA1c cannot be fooled by last-minute dieting.
Frequently Asked Questions About A1C
Related Clinical & Nutrition Calculators
Related Calculators & Companion Tools
Complementary tools designed to pair with the A1C & Estimated Average Glucose Calculator. Compare formulas and verify your projections.
BMI Calculator (Men & Women)
Calculate your Body Mass Index (BMI) in lbs/inches or metric with adult Male & Female CDC charts, healthy weight ranges, and athletic adjustments.
Body Fat Calculator
Estimate your body fat percentage, lean body mass, and fat mass using U.S. Navy tape measurements.
Ideal Weight Calculator
Estimate your ideal healthy body weight range using multiple clinical formulas (Devine, Robinson, Miller, Hamwi).
Pregnancy Calculator
Calculate your estimated due date based on your last menstrual period and gestational age.
Was this calculator accurate & helpful?
Interactive Google Health Web Stories & Visual Guides
Explore fast, mobile-first visual stories on BMI, Calorie Deficit, TDEE, Macros, Sleep Cycles, and Healthy Habits.
Evidence-Based Clinical Formulations
All biometrics, body composition, and caloric computations adhere to the Mifflin-St Jeor, Harris-Benedict, and U.S. Navy standards referenced by the Centers for Disease Control and Prevention.
Cardiovascular & Nutrition Tips
Target heart rates, daily sodium ceilings, and macronutrient distributions align with the American Heart Association (AHA) and USDA Dietary Guidelines for Americans.
Practical Health Takeaways
Pair your calculation with structured sleep (7-9 hrs), balanced hydration (half body weight in oz), and a 500 kcal sustainable deficit for healthy body composition management.