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Estimated Average Glucose Calculator

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Convert your A1c percentage into estimated average glucose (eAG) in mg/dL and mmol/L using the published ADAG study formula, with diabetes category context.

A1c
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4%15%

A1c reflects average blood glucose over roughly the prior 2-3 months. The ADAG formula converts it to an estimated average glucose (eAG) figure comparable to a glucose meter reading.

Estimated Average Glucose

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0 mmol/L

A1c Category

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For informational purposes only. Not a substitute for lab testing or professional medical advice — consult a healthcare provider for diagnosis.

What is a eAG Calculator?

An Estimated Average Glucose (eAG) Calculator converts your hemoglobin A1c percentage into an estimated average blood glucose figure, expressed in the same mg/dL or mmol/L units shown on a standard glucose meter. A1c reflects the percentage of hemoglobin proteins in red blood cells that have glucose attached, which builds up gradually and reflects average blood sugar exposure over roughly the prior two to three months rather than any single reading.

This calculator applies the ADAG (A1c-Derived Average Glucose) study formula published by Nathan et al. in 2008, the same conversion many clinical labs use to report eAG alongside A1c results. It pairs naturally with the A1c Calculator, which runs the conversion in the opposite direction — from average glucose back to an estimated A1c.

How to use this eAG Calculator calculator

  1. Enter your A1c percentage from a recent lab result.
  2. Review the Estimated Average Glucose (mg/dL) result, shown as the primary output.
  3. Check the Estimated Average Glucose (mmol/L) value if you track glucose in international units.
  4. Review the A1c Category to see whether your value falls in the normal, prediabetes, or diabetes range.
  5. Compare the eAG figure to your glucose meter or CGM average as a general reference point, and discuss any meaningful differences with a healthcare provider.

Formula & Methodology

eAG (mg/dL) = 28.7 × A1c(%) − 46.7

This is the ADAG study formula (Nathan et al., Diabetes Care, 2008), derived from correlating A1c values with average glucose measured by frequent glucose monitoring across a large study population.

eAG (mmol/L) = eAG (mg/dL) ÷ 18.0182

Worked example: for an A1c of 6.5%:
- eAG = 28.7 × 6.5 − 46.7 = 139.8 mg/dL
- eAG in mmol/L = 139.8 ÷ 18.0182 = 7.76 mmol/L
- Since 6.5% is at the diabetes diagnostic threshold, the category shown is Diabetes range.

Frequently Asked Questions

Estimated average glucose (eAG) is a value, expressed in the same mg/dL or mmol/L units as a glucose meter, that represents your average blood sugar over roughly the past two to three months. It is derived directly from your A1c percentage using a formula developed in the ADAG (A1c-Derived Average Glucose) study.
eAG in mg/dL is calculated as 28.7 times your A1c percentage minus 46.7, a formula published by Nathan et al. in the 2008 ADAG study. The mg/dL figure can then be converted to mmol/L by dividing by 18.0182, the standard glucose unit conversion factor.
A1c is reported as a percentage, which doesn't map intuitively to the mg/dL or mmol/L numbers most people see on a glucose meter or continuous glucose monitor. eAG translates A1c into those familiar units, making it easier to relate lab results to daily glucose readings.
eAG approximates your true average glucose over the prior two to three months, while a meter or CGM average only reflects the days or weeks you actually tested. Differences between the two can occur due to testing patterns, red blood cell lifespan variation, or conditions affecting A1c accuracy.
This calculator accepts A1c values from 4% to 15%, covering the full range from well below normal to values seen in poorly controlled diabetes. Typical results fall between roughly 68 mg/dL at 4% A1c and 382 mg/dL at 15% A1c.
An A1c below 5.7% is generally considered normal, 5.7% to 6.4% falls in the prediabetes range, and 6.5% or higher is in the diabetes diagnostic range according to American Diabetes Association criteria. These categories provide context alongside the eAG conversion.
You can compare your calculated eAG to your glucose meter or CGM average as a rough sanity check, but meaningful discrepancies should be discussed with a healthcare provider rather than interpreted independently. Testing frequency, timing, and individual physiology can all cause the two figures to diverge.
Yes — many labs now report eAG alongside A1c on lab result printouts using this same ADAG-derived formula. This calculator lets you reproduce that conversion instantly from any A1c value.
eAG reflects average blood glucose control, while a measure like the [HOMA-IR Calculator](/homa-ir-calculator/) estimates insulin resistance from fasting glucose and insulin together. Both are complementary pieces of the broader picture of metabolic health rather than interchangeable measures.
Use whichever unit matches your glucose meter or regional convention — the US typically uses mg/dL, while many other countries use mmol/L. This calculator provides both automatically so you can compare against either unit system.
No — eAG is a mathematical conversion of A1c and should be interpreted alongside a full clinical evaluation, not used alone for diagnosis. A qualified healthcare provider should confirm any diabetes or prediabetes diagnosis using validated lab testing and clinical judgment.
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