Hemoglobin A1C (HbA1c) reflects your average blood glucose over the past 2-3 months. When glucose circulates in the blood, some of it binds irreversibly to hemoglobin in red blood cells. Because red blood cells live about 90-120 days, measuring how much glucose has attached gives a stable picture of long-term control — not a snapshot like a single fingerstick.

How is A1C converted to estimated average glucose (eAG)?

The ADAG (A1C-Derived Average Glucose) study produced the accepted formula: eAG (mg/dL) = 28.7 × A1C − 46.7. For example, an A1C of 6.0% corresponds to an average glucose of roughly 126 mg/dL (7.0 mmol/L). This calculator uses that validated conversion.

What are the A1C diagnostic ranges?

The American Diabetes Association uses: normal < 5.7%, prediabetes 5.7-6.4%, and diabetes ≥ 6.5%. For people with diabetes, most clinicians target < 7% for general management, with tighter goals for younger patients and looser goals for older patients with comorbidities.

Why does my A1C not match my daily glucose readings?

A1C is a weighted average across 90 days, but the most recent 30 days contribute about half of the result. If your glucose has been swinging wildly, A1C can look fine while average excursions are not — this is why continuous glucose monitoring (CGM) and time-in-range are increasingly used alongside A1C.

Can A1C be misleading?

Yes. Anything that changes red blood cell lifespan affects it. Anemia, recent blood loss, pregnancy, hemoglobin variants (common in people of African, Mediterranean, or Southeast Asian descent), and chronic kidney disease can all push A1C higher or lower than true average glucose. If something seems off, ask about fructosamine or a CGM instead.

What is mmol/mol? I see it on my labs.

Outside the US, A1C is often reported in IFCC units (mmol/mol) instead of percent. Conversion: IFCC = (NGSP − 2.152) / 0.09148. So an A1C of 7.0% equals 53 mmol/mol. We show both here.

A1C to Average Glucose (eAG) Converter

Convert HbA1c to estimated average glucose using the ADAG formula.

Converter

Understanding A1C

A1C is the most common marker clinicians use to diagnose and track diabetes. It measures the percentage of hemoglobin molecules that have glucose permanently attached — essentially, how much your red blood cells have been "candied" by circulating sugar over the last 2-3 months.

The Conversion Formula

eAG (mg/dL) = 28.7 × A1C − 46.7

eAG (mmol/L) = eAG (mg/dL) ÷ 18.0156

This linear relationship comes from the 2008 ADAG (A1C-Derived Average Glucose) study — 507 participants with continuous glucose monitoring over 12 weeks, correlated against A1C. It's now the standard conversion recognized by the ADA and IDF.

Diagnostic Ranges (ADA)

Category	A1C	eAG (mg/dL)
Normal	< 5.7%	< 117
Prediabetes	5.7 – 6.4%	117 – 137
Diabetes	≥ 6.5%	≥ 140
Typical diabetes goal	< 7.0%	< 154

What Moves A1C

Diet: reducing refined carbs and added sugars has the largest short-term effect
Exercise: post-meal walks blunt glucose spikes; regular aerobic training improves insulin sensitivity
Weight loss: even 5-7% bodyweight loss can drop A1C by 0.5-1.0 points in people with prediabetes
Sleep: poor sleep raises morning glucose and insulin resistance within days
Medication adherence when prescribed

Not a Diagnosis

This converter is educational. A single lab value is not a diagnosis, and A1C can be skewed by anemia, hemoglobin variants, and kidney disease. Use results to understand your labs and discuss them with your clinician.

A1C to Average Glucose (eAG) Converter

Understanding A1C

The Conversion Formula

Diagnostic Ranges (ADA)

What Moves A1C

Not a Diagnosis

Frequently Asked Questions

Related Calculators

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Track Your A1C Over Time