Convert your A1C (HbA1c) to estimated average glucose (eAG) using the ADA-validated ADAG formula, or convert average glucose back to A1C.
The A1C test (also called HbA1c or glycated hemoglobin) measures the percentage of hemoglobin in your blood that has glucose attached to it. Because red blood cells live for approximately 2-3 months, the A1C reflects your average blood sugar level over that period. Unlike a fasting glucose test, which captures a single moment, the A1C provides a comprehensive picture of blood sugar management over time.
This calculator converts between A1C percentage and estimated average glucose (eAG) using the formula from the A1C-Derived Average Glucose (ADAG) study. Enter an A1C percentage to see the equivalent average blood sugar in mg/dL and mmol/L, or enter a blood sugar value to see the equivalent A1C. The calculator also shows your risk category (normal, prediabetes, or diabetes) based on American Diabetes Association diagnostic criteria.
The American Diabetes Association uses these diagnostic thresholds: Below 5.7% is normal, indicating healthy blood sugar regulation. 5.7% to 6.4% is prediabetes, indicating increased risk that warrants lifestyle intervention. 6.5% or higher on two separate tests is diagnostic for Type 2 diabetes. These thresholds are based on large population studies showing that the risk of diabetic complications, particularly retinopathy, rises sharply above 6.5%.
For most non-pregnant adults with diabetes, the ADA recommends a target A1C of below 7.0%. More aggressive targets (below 6.5%) may be appropriate for younger patients early in their diagnosis. More relaxed targets (below 8.0%) may be appropriate for older adults, those with multiple chronic conditions, or those with a history of severe hypoglycemia. During pregnancy, the target is below 6.0% if achievable without significant hypoglycemia. These targets should always be individualized in consultation with your healthcare provider.
Several conditions can cause misleading A1C results. Hemoglobin variants (sickle cell trait, hemoglobin C) can interfere with certain testing methods. Iron-deficiency anemia can falsely lower A1C because red blood cells turn over faster. Chronic kidney disease can falsely elevate A1C. Recent blood transfusions introduce red blood cells with different glycation histories. If your A1C seems inconsistent with your daily glucose readings, discuss these factors with your doctor. The eGFR Calculator can help estimate kidney function from a basic metabolic panel.
A1C (also called HbA1c or hemoglobin A1c) reflects your average blood sugar over the past 2 to 3 months. The conversion between A1C percentage and estimated average glucose (eAG) in mg/dL uses the ADAG formula: eAG (mg/dL) = 28.7 x A1C - 46.7. Here are common conversions:
A1C 5.0% = 97 mg/dL (normal). 5.5% = 111 mg/dL (normal). 5.7% = 117 mg/dL (prediabetes threshold). 6.0% = 126 mg/dL (prediabetes). 6.5% = 140 mg/dL (diabetes threshold). 7.0% = 154 mg/dL (common treatment target). 8.0% = 183 mg/dL. 9.0% = 212 mg/dL. 10.0% = 240 mg/dL. Enter your A1C or blood glucose value above to convert in either direction.
Below 5.7%: Normal. Low risk of diabetes. 5.7% to 6.4%: Prediabetes. Elevated risk of developing type 2 diabetes. Lifestyle interventions (diet, exercise, weight loss) can reduce or delay progression. 6.5% and above: Diabetes. Diagnosis is confirmed with two separate tests showing A1C at or above 6.5%. For people already diagnosed with diabetes, the American Diabetes Association recommends a target A1C below 7.0% for most adults, though individual targets may vary. The Blood Sugar Calculator provides additional context for interpreting individual glucose readings.
Hemoglobin A1c measures the percentage of hemoglobin proteins in your blood that have glucose attached to them (glycated hemoglobin). Since red blood cells live approximately 90 to 120 days, the A1C test captures a weighted average of blood sugar levels over that period, with more recent weeks weighted more heavily. This makes A1C more stable than a single fasting glucose reading, which can fluctuate based on meals, stress, and time of day. However, certain conditions can affect A1C accuracy: iron deficiency anemia, sickle cell trait, recent blood loss, and pregnancy can all cause A1C to read higher or lower than expected.