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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.

Reviewed by the thecalcu.com team · Last updated July 17, 2026

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.

Why Use an Estimated Average Glucose Calculator?

A1c percentages don't translate intuitively into the day-to-day glucose numbers people see on a meter or continuous glucose monitor, which makes it hard to connect lab results to daily self-monitoring. Converting A1c to eAG closes that gap, giving a mg/dL or mmol/L figure that's directly comparable to routine readings.

This is especially useful right after a lab visit, when an A1c result arrives as a percentage but the more familiar reference point is a glucose number. It also works well alongside the Diabetes Risk Calculator for a broader picture of glucose-related risk factors.

Who Should Use This Calculator?

  • Anyone who just received A1c lab results and wants to see what that percentage means in everyday glucose terms.
  • People with diabetes or prediabetes comparing their A1c-derived average against their glucose meter or CGM data.
  • Caregivers helping interpret lab reports for a family member managing diabetes.
  • Students and healthcare trainees learning how the ADAG formula links A1c to average glucose.

This tool is for informational and educational purposes only and is not a substitute for professional medical diagnosis or treatment, always consult a qualified healthcare provider to interpret your A1c results and glucose management plan.

What Insights Does the eAG Calculator Give You?

  • Estimated Average Glucose (mg/dL), the primary conversion result, showing your approximate average blood glucose in the unit most US glucose meters use.
  • Estimated Average Glucose (mmol/L), the same result converted to the unit commonly used outside the US, useful for comparing against international lab reports.
  • A1c Category, a quick normal, prediabetes, or diabetes-range classification based on your entered A1c, giving immediate diagnostic context alongside the glucose conversion.

Together, these outputs let you see both what your A1c number means in daily glucose terms and where it falls relative to standard diagnostic thresholds.

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.
Show formula & methodology ↓Show less ↑

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

What is estimated average glucose (eAG)?
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.
How is eAG calculated from A1c?
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.
Why convert A1c to eAG instead of just reading the A1c percentage?
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.
Is eAG the same as my average glucose meter reading?
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.
What A1c range does this calculator cover?
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.
What do the A1c categories mean?
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.
Can I use this calculator to check my glucose meter accuracy?
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.
Is this the same formula labs use to report eAG on my results?
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.
How does eAG relate to HOMA-IR and insulin resistance?
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.
Should I convert eAG to mmol/L or use mg/dL?
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.
Can eAG diagnose diabetes on its own?
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.
Also known as
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