Convert HbA1c percentage to estimated average glucose (eAG) in mg/dL and mmol/L using the ADAG study formula. Classify your A1c level.
This calculator converts HbA1c to estimated average glucose (eAG) using the ADAG study equation. It reports the result in both mg/dL and mmol/L so a lab A1c value can be compared more easily with everyday glucose-meter units.
The page also shows the common ADA threshold bands for normal, prediabetes, and diabetes. That makes it useful for translating an A1c result into more familiar glucose terms, while still keeping the interpretation at a broad educational level.
A1c and fingerstick glucose use different units and different time horizons. Converting A1c to eAG gives a quick bridge between lab results and meter-style numbers without doing the ADAG math manually.
ADAG Study Formula (Nathan et al., 2008): eAG (mg/dL) = 28.7 × HbA1c − 46.7 eAG (mmol/L) = 1.5944 × HbA1c − 2.5944 A1c Classification (ADA): • Normal: < 5.7% • Prediabetes: 5.7–6.4% • Diabetes: ≥ 6.5% Target for most diabetics: < 7.0% (eAG ~154 mg/dL)
Result: eAG = 154 mg/dL (8.6 mmol/L) — Diabetes range
eAG = 28.7 × 7.0 − 46.7 = 200.9 − 46.7 = 154.2 mg/dL. The page labels 7.0% in the diabetes range and translates it into a meter-style average glucose value. Personal glucose targets still depend on the broader diabetes plan rather than on this conversion alone.
The A1c-Derived Average Glucose (ADAG) study established the modern formula for translating HbA1c into estimated average glucose. That is what this page does: it turns a lab percentage into a meter-style number in mg/dL and mmol/L so the result is easier to compare with everyday glucose readings.
A1c and meter averages do not always line up perfectly. Anemia, altered red-cell lifespan, kidney disease, hemoglobin variants, pregnancy, and recent transfusion can all make the A1c-to-eAG translation less reliable.
This page is best used to convert between HbA1c and average glucose language. It is not a medication-target engine and it does not replace individual goals set from meter data, CGM trends, or the broader diabetes workup.
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This page converts HbA1c to estimated average glucose using the ADAG equation, then reports the result in both mg/dL and mmol/L. It also maps the entered HbA1c value to broad ADA threshold bands for normal, prediabetes, and diabetes classification.
The result is a translation tool, not a replacement for individualized diabetes management. HbA1c can be misleading in some settings, including anemia, hemoglobin variants, kidney disease, pregnancy, or recent blood loss, so the output should be read with the broader clinical picture.
HbA1c (glycated hemoglobin) measures the percentage of hemoglobin proteins in your blood that have glucose attached. Since red blood cells live about 3 months, HbA1c reflects your average blood sugar over that period. It's a more stable metric than a single glucose reading.
Below 5.7% is normal. Between 5.7% and 6.4% indicates prediabetes. 6.5% or higher on two separate tests is used for diabetes diagnosis. Personal treatment targets may differ from those diagnostic cutoffs.
The ADAG formula (Nathan et al., 2008) was derived from a study of 507 participants using continuous glucose monitors. The correlation between A1c and average glucose was r = 0.92. It's considered the best available conversion, though individual variation exists.
Several factors cause discordance: testing frequency and timing (you may miss highs/lows), hemoglobin variants (HbS, HbC), iron deficiency anemia, kidney disease, or pregnancy. If your A1c seems inconsistent with your meter data, discuss alternative monitoring with your provider.
Because A1c reflects a 2–3 month average, it takes about that long to see meaningful changes. The most recent 30 days have the greatest influence. Significant dietary and medication changes can shift A1c by 0.5–1.0% in a quarter.
Each 1% change in HbA1c corresponds to roughly 29 mg/dL (1.6 mmol/L) change in estimated average glucose. That translation is useful for understanding the scale of the difference, but the clinical meaning depends on the broader diabetes context.