🩸 A1C to eAG Converter – Translate Blood Sugar Numbers
The A1C to eAG Converter bridges two common ways of measuring long-term blood glucose control. A1C (glycated hemoglobin, or HbA1c) is reported as a percentage by laboratories; eAG (estimated average glucose) expresses the same information in the familiar units of a home glucose meter — mg/dL or mmol/L. This converter lets patients, clinicians, and students move instantly between both representations using the validated ADAG formula.
📐 The ADAG Formulas
The American Diabetes Association (ADA) and the European Association for the Study of Diabetes (EASD) endorse the following equations, derived from the landmark 2008 A1C-Derived Average Glucose (ADAG) study:
eAG (mg/dL) = 28.7 × A1C (%) − 46.7
eAG (mmol/L) = eAG (mg/dL) ÷ 18.0182
A1C (%) = (eAG mg/dL + 46.7) ÷ 28.7For example, an A1C of 7.0% yields an eAG of approximately 154 mg/dL or 8.6 mmol/L. Conversely, a meter average of 126 mg/dL corresponds to an estimated A1C of roughly 6.0%.
🔄 Three Conversion Modes
A1C → eAG
Enter any A1C percentage (3–20%) to receive the equivalent average glucose in both mg/dL and mmol/L. This is the most common direction — useful after receiving a lab result and wanting to understand it in everyday glucose terms.
eAG → A1C
Enter an average glucose reading from a continuous glucose monitor (CGM) or from manually averaged meter readings. Select whether the value is in mg/dL or mmol/L, and the converter estimates the corresponding A1C percentage using the inverse ADAG formula.
Target Comparison
Enter both your current A1C and a desired target A1C. The tool calculates the absolute gap in percentage points and the equivalent eAG difference in mg/dL and mmol/L, along with a plain-language summary — ideal for goal-setting conversations with a healthcare provider.
📊 A1C Reference Ranges
| A1C Range | eAG (mg/dL) | eAG (mmol/L) | Clinical Category |
|---|---|---|---|
| < 5.7% | < 117 | < 6.5 | Normal |
| 5.7 – 6.4% | 117 – 137 | 6.5 – 7.6 | Pre-diabetes |
| 6.5 – 6.9% | 140 – 151 | 7.8 – 8.4 | Diabetes, at/near ADA target |
| 7.0 – 7.9% | 154 – 180 | 8.6 – 10.0 | Above common ADA target |
| ≥ 8.0% | ≥ 183 | ≥ 10.2 | Poorly controlled |
⚠️ Limitations and Clinical Context
The ADAG formula explains about 84% of variance in mean glucose, meaning individual results may differ by ±15–20 mg/dL from the formula estimate. Accuracy can be reduced in patients with:
- Hemoglobin variants (e.g., HbS, HbC) that affect red-blood-cell lifespan
- Iron-deficiency anemia or hemolytic conditions
- Chronic kidney disease affecting erythrocyte turnover
- Recent blood transfusions
This tool is designed for educational and self-monitoring purposes only. All medical decisions — including adjusting diabetes medications or diagnosing diabetes — should be made in consultation with a qualified healthcare professional.
💡 Tips for Using This Tool
- Use A1C → eAG mode after your quarterly lab test to immediately visualize what that percentage means in daily glucose terms.
- If your CGM provides a GMI (Glucose Management Indicator), it is already an A1C estimate — you can enter it directly or use the eAG → A1C mode with your CGM average.
- In Target Comparison mode, a gap of 1 A1C percentage point corresponds to roughly
28.7 mg/dL(1.6 mmol/L) in average glucose. - Toggle Show Formula Steps to see exactly how each value is derived — useful for students learning clinical biochemistry.