Estimated Average Glucose (eAG) Calculator

Convert your HbA1c (%) into estimated average glucose — in mg/dL and mmol/L — using the Nathan 2008 (ADAG study) equation trusted by the American Diabetes Association. Free, instant, and 100% private in your browser.

Estimate, not medical advice. eAG comes from a population regression — your true average can differ. Diabetes care decisions should always follow your clinician, not this calculator.

eAG Calculator

HbA1c (%)

—

mg/dL estimated average glucose

— mmol/L · — mmol/mol (IFCC)

—

Remember: this is a population-based estimate, not medical advice. Manage diabetes only with your clinician.

Worked example

A1C = 7.0% → eAG = 28.7 × 7.0 − 46.7 = 154.2 mg/dL
154.2 ÷ 18.0156 = 8.56 mmol/L · IFCC = 53 mmol/mol

Numbers above are computed by this page's engine from the ADAG equation — not typed by hand.

What your eAG means

A1C range	eAG (mg/dL)	eAG (mmol/L)	Interpretation
< 5.7%	< 116.9	< 6.5	Below diabetes range
5.7–6.4%	116.9–137.0	6.5–7.6	Prediabetes range
≥ 6.5%	≥ 139.9	≥ 7.8	Diabetes range (diagnostic criterion is A1C ≥ 6.5% on repeat testing)

For many adults with diabetes the ADA target is A1C below 7.0% — roughly eAG below 154.2 mg/dL (8.6 mmol/L). Individual targets differ; ask your clinician.

A1C ↔ eAG reference table

Every row is computed from the ADAG equation. The highlighted row is closest to your current input.

A1C (%)	eAG (mg/dL)	eAG (mmol/L)
4.5%	82.5	4.6
5.0%	96.8	5.4
5.5%	111.2	6.2
6.0%	125.5	7.0
6.5%	139.9	7.8
7.0%	154.2	8.6
7.5%	168.6	9.4
8.0%	182.9	10.2
8.5%	197.3	10.9
9.0%	211.6	11.7
9.5%	226.0	12.5
10.0%	240.3	13.3
10.5%	254.7	14.1
11.0%	269.0	14.9
11.5%	283.4	15.7
12.0%	297.7	16.5

Limitations — read before trusting the number

Population estimate, not your value. The ADAG equation is a regression line through ~500 people; any individual's true average can sit meaningfully above or below it.
Anything that changes red-blood-cell lifespan changes A1C — anemia, iron/B12 treatment, hemoglobinopathies (e.g. sickle-cell trait), chronic kidney disease / dialysis, pregnancy, recent blood loss or transfusion.
Assay differences. Some hemoglobin variants interfere with certain A1C lab methods; marked discordance between A1C and your meter readings deserves a lab-method review with your clinician.
It reflects ~2–3 months, weighted toward recent weeks — a single bad week barely moves it, and a single good week barely fixes it.
eAG does not diagnose diabetes and does not replace fasting glucose, OGTT, or your clinician's judgment.

Frequently asked questions

What is estimated average glucose (eAG) and how is it calculated?

eAG translates your HbA1c percentage into the blood-sugar units you see on a glucose meter. The formula comes from the ADAG study (Nathan et al., Diabetes Care 2008): eAG (mg/dL) = 28.7 × A1C − 46.7. Example: A1C 7.0% → 28.7 × 7.0 − 46.7 = 154.2 mg/dL, which is 8.56 mmol/L (154.2 ÷ 18.0156).

How accurate is eAG?

It is a population regression estimate, not a measurement. In the ADAG study the regression explained most of the variation (r² ≈ 0.84) and about 90% of participants' true averages fell within ±15% of the estimate — but individual glycation rates differ, so your true average can be meaningfully higher or lower. Conditions that alter red-blood-cell turnover (anemia, hemoglobinopathies, kidney disease, pregnancy, blood loss/transfusion) shift the relationship further.

Why does my eAG differ from my meter or CGM average?

Three common reasons: (1) people glycate hemoglobin at slightly different rates for the same glucose level; (2) eAG weights roughly the last 2–3 months while your meter average covers whatever period you choose; (3) fingerstick averages miss overnight and between-meal values that A1C captures. A large, persistent mismatch is worth discussing with your clinician — it can signal an A1C assay issue.

Which conditions make A1C — and therefore eAG — unreliable?

Anything that shortens or lengthens red-blood-cell life: anemia and iron/B12 treatment, hemoglobinopathies such as sickle-cell trait, chronic kidney disease / dialysis, pregnancy, and recent blood loss or transfusion. Some hemoglobin variants also interfere analytically with certain lab methods. In these situations clinicians use alternative markers (e.g. fructosamine or glycated albumin) or rely on direct glucose data instead.

What eAG corresponds to the ADA A1C target?

For many adults with diabetes the ADA target is A1C below 7.0%, which is eAG below 154.2 mg/dL (8.6 mmol/L). Targets are individualized — older adults, people with hypoglycemia risk, or limited life expectancy often have looser targets, and pregnancy has tighter ones. Never change treatment to chase a calculator number; follow your clinician's plan.

Why are there two different mmol/L values for the same A1C?

The paper publishes the regression in both unit systems: the direct mmol/L fit gives eAG = 1.59 × A1C − 2.59, which for A1C 7.0% yields 8.54 mmol/L. Converting the mg/dL result instead (154.2 ÷ 18.0156) gives 8.56 mmol/L. The two fits differ by a couple of hundredths — pure regression noise. This calculator shows the converted value, consistent with the ADA's own eAG calculator.

Can eAG diagnose diabetes or prediabetes?

No. Diagnosis uses A1C itself (≥ 6.5% on repeat testing), fasting plasma glucose, or the oral glucose tolerance test — per ADA criteria. eAG is a communication aid that puts the same A1C number into friendlier units. For context: prediabetes (A1C 5.7–6.4%) corresponds to roughly 116.9–137.0 mg/dL, and the diabetes threshold (A1C 6.5%) to about 139.9 mg/dL.

Estimated Average Glucose (eAG) Calculator

eAG Calculator

Worked example

What your eAG means

A1C ↔ eAG reference table

Limitations — read before trusting the number

Frequently asked questions

What is estimated average glucose (eAG) and how is it calculated?

How accurate is eAG?

Why does my eAG differ from my meter or CGM average?

Which conditions make A1C — and therefore eAG — unreliable?

What eAG corresponds to the ADA A1C target?

Why are there two different mmol/L values for the same A1C?

Can eAG diagnose diabetes or prediabetes?

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