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Estimated Average Glucose Calculator

Ready to calculate
ADAG Formula.
mg/dL & mmol/L.
ADA Category Thresholds.
100% Free.
No Data Stored.

How it Works

01Diabetes Status

Tell the calculator if you have a diabetes diagnosis

02Enter HbA1c

Your most recent HbA1c value in percent

03Convert to eAG

eAG = 28.7 × A1c − 46.7 (mg/dL) · 1.59 × A1c − 2.59 (mmol/L)

04Read Category

Normal · Prediabetes · Diabetes (at target or above target)

About the Estimated Average Glucose Calculator

The Estimated Average Glucose (eAG) Calculator converts your HbA1c percentage into an everyday blood-glucose number (mg/dL or mmol/L). HbA1c reflects the average glucose your red blood cells have been bathed in over the past ~3 months. eAG translates that abstract percentage into a number you'd recognize from a glucose meter — making it intuitive to compare to daily readings.


Enter your HbA1c percentage. The calculator returns eAG in both mg/dL (US standard) and mmol/L (international) using the validated ADA conversion equation: eAG = (28.7 × A1c) − 46.7. It also shows the diabetes diagnostic bands and the contextual interpretation.

How the Calculator Works

Enter HbA1c as a percentage (e.g., 7.0).
Apply the ADA equation: eAG (mg/dL) = (28.7 × A1c) − 46.7.
Convert to mmol/L for international readers: divide by 18.018.
Read the diabetes band — non-diabetic, prediabetic, diabetic, poor control.
Compare to your meter readings to validate that your A1c lines up with daily glucose.

The ADA Equation

eAG (mg/dL) = (28.7 × A1c%) − 46.7


From the 2008 Nathan et al. linear regression of HbA1c vs. continuous glucose monitoring data across 507 individuals.


Convert: eAG (mmol/L) = eAG (mg/dL) ÷ 18.018. ADA diagnostic bands: A1c <5.7% non-diabetic · 5.7–6.4% prediabetic · ≥6.5% diabetic.

Real-World Example

Worked Example

HbA1c = 6.5%:

StepCalculationResult
eAG (mg/dL)(28.7 × 6.5) − 46.7139.85
Rounded—140 mg/dL
mmol/L140 ÷ 18.0187.77 mmol/L
BandA1c ≥ 6.5%Diabetes diagnostic threshold

Who Uses It

1
🩺 Diabetes Patients: Make sense of A1c results in everyday glucose terms.
2
💊 Endocrinologists: Quick patient-education tool.
3
📊 CGM Users: Compare CGM time-in-range averages to A1c-derived eAG.
4
🥗 Diabetes Educators: Translate clinical numbers into something intuitive.
5
💼 Insurance / Disability: Convert reports between US and international units.
6
📈 Self-Trackers: Validate that meter or CGM averages match lab A1c.

Final Thoughts

HbA1c is the gold standard for long-term glycemic control, but the percentage doesn't mean much if you live with daily glucose readings. The eAG conversion translates A1c into the same unit as your meter — instantly more interpretable. The ToolsACE eAG Calculator runs the ADA's official equation, no spreadsheets required.

Frequently Asked Questions

Why doesn't eAG match my meter average exactly?
Several reasons: (1) meters sample fasting/post-meal asymmetrically, (2) A1c reflects 3 months while meter averages may be from a few weeks, (3) red blood cell turnover affects A1c independently. A 10–15 mg/dL discrepancy is common and not concerning.
Is eAG the same as 'average blood sugar'?
Effectively, yes — eAG is the model-derived average. Continuous glucose monitor (CGM) averages over 90 days are the closest direct comparison.
What A1c is 'in target' for diabetes?
ADA recommends <7% for most adults with diabetes; some patients aim for <6.5% if achievable without hypoglycemia. Older or frail patients may target <8%. eAG of <154 mg/dL corresponds to A1c <7%.
Is the equation accurate for everyone?
It was derived from 507 mostly type 1, type 2, and non-diabetic adults. It's less validated for: pregnant women, people with hemoglobinopathies (sickle cell, thalassemia), recent transfusions, severe anemia, or non-Caucasian populations where A1c-glucose relationships can subtly differ.
Can I trust A1c if I have anemia?
No — interpret with caution. Conditions that change red blood cell lifespan (anemias, recent blood loss, hemodialysis) can falsely raise or lower A1c. Talk to your provider about alternatives like fructosamine or CGM-derived metrics.
What's the prediabetic range?
A1c 5.7–6.4% (eAG ~117–137 mg/dL). At this stage, meaningful diabetes prevention is possible — lifestyle changes can revert A1c back to <5.7% in many cases.
How often should A1c be checked?
Every 3 months for unstable diabetes, every 6 months when controlled. Less than every 3 months won't capture changes — A1c reflects the past 8–12 weeks.
Why does the formula give a non-integer?
Because it's a regression equation. The result is rounded for clinical use. The calculator shows both raw and rounded values.
What's the difference between eAG and ADAG?
eAG is the term in clinical use today. ADAG (A1c-Derived Average Glucose) was the name of the 2008 study that established the conversion. Same concept.
Is my data private?
Yes. The calculator runs locally in your browser. No data is stored or transmitted.

Author Spotlight

The ToolsACE Team - ToolsACE.io Team

The ToolsACE Team

Our health tools team implements the validated A1c-Derived Average Glucose (ADAG) conversion formula — eAG = 28.7 × A1c − 46.7 in mg/dL — derived from continuous glucose monitoring across 507 subjects. This is the formula used clinically to translate HbA1c values into the everyday glucose units patients read on meters.

ADAG Trial Conversion FormulaADA A1c Diagnostic CriteriaSoftware Engineering Team

Medical Disclaimer

eAG is a model-based estimate. Treatment decisions for diabetes require clinical interpretation by a healthcare provider — never adjust medications based solely on a calculator result.