Convert HbA1c to estimated average glucose (eAG) in mg/dL or mmol/L, or reverse-calculate A1c from average glucose. Includes ADA diabetes thresholds.
Estimated average glucose (eAG) translates the HbA1c percentage into an average blood glucose value that patients can more easily understand and relate to their daily glucose meter readings. While HbA1c reflects the average blood glucose over the previous 2–3 months (the lifespan of a red blood cell), many patients find it difficult to conceptualize what an A1c of 7% actually means in terms of their day-to-day blood sugar numbers.
The ADAG (A1c-Derived Average Glucose) study established the validated conversion formula: eAG (mg/dL) = 28.7 × A1c − 46.7. This linear relationship was derived from continuous glucose monitoring data correlated with simultaneous A1c measurements in a diverse population of diabetic and non-diabetic individuals.
This calculator converts bidirectionally between HbA1c and estimated average glucose, displays results in both mg/dL and mmol/L, and categorizes the result according to ADA (American Diabetes Association) diagnostic criteria. It also estimates the Glucose Management Indicator (GMI) and approximate time-in-range for patients using continuous glucose monitors. The tool is designed to help both clinicians and patients understand glycemic control in practical terms.
This calculator helps patients and clinicians translate between HbA1c and average glucose values for clearer understanding of long-term glycemic control. It supports diabetes education by placing A1c results in the context of daily glucose readings. Keep these notes focused on your operational context. Tie the context to the calculator’s intended domain. Use this clarification to avoid ambiguous interpretation.
eAG (mg/dL) = 28.7 × HbA1c − 46.7. eAG (mmol/L) = eAG (mg/dL) ÷ 18.0182. Reverse: HbA1c = (eAG + 46.7) ÷ 28.7. GMI = 3.31 + 0.02392 × mean glucose (mg/dL).
Result: eAG = 154 mg/dL (8.6 mmol/L). Diabetes, controlled.
HbA1c of 7.0% converts to eAG = 28.7 × 7.0 − 46.7 = 154 mg/dL. This is the ADA target for most adults with diabetes, indicating reasonably controlled glucose levels over the past 2–3 months.
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eAG is the estimated average blood glucose based on HbA1c. It represents the average glucose concentration over the previous 2–3 months, weighted toward more recent weeks.
No. Fasting glucose is a single point-in-time measurement, while eAG reflects the average of all glucose levels (fasting and post-meal) over months. eAG is typically higher than fasting glucose.
Self-monitoring often captures fasting or pre-meal values, which are lower than the true 24-hour average. Post-meal spikes and overnight values are frequently missed, leading to a lower meter average than eAG.
Yes. Hemolytic anemia, iron deficiency, blood transfusions, hemoglobin variants (HbS, HbC), and pregnancy can all falsely raise or lower A1c independent of glucose control.
The ADA recommends A1c <7% for most adults with diabetes. Less stringent targets (<8%) may be appropriate for elderly patients or those with frequent hypoglycemia. More stringent (<6.5%) targets apply in selected younger patients.
Glucose Management Indicator (GMI) is an A1c-equivalent calculated from continuous glucose monitor (CGM) data. It may differ from lab A1c because it reflects a different time window (typically 14 days vs. 2–3 months).