HEALTHLab ValuesHealth Calculator
🩸

HbA1c Calculator

Convert between HbA1c and estimated average glucose (eAG). HbA1c reflects 2-3 month average blood sugar: normal is below 5.7%, prediabetes 5.7-6.4%, diabetes ≥6.5% (ADA criteria).

Did our AI summary help? Let us know.

HbA1c reflects 2-3 month average blood sugar.

Ready to run the numbers?

Why: HbA1c reflects 2-3 month average blood sugar.

How: Enter your values in the calculator fields below, keep units consistent, then run the calculation to see results and any step-by-step work shown on this page.

Run the calculator when you are ready.

Calculate Your HealthUse the calculator below to check your health metrics

📋 Quick Examples — Click to Load

Enter 3-20
%
Enter HbA1c between 3 and 20%

For informational purposes only — not medical advice. Consult a healthcare professional before acting on results.

HbA1c reflects 2-3 month average blood sugar. ADA criteria: normal <5.7%, prediabetes 5.7-6.4%, diabetes ≥6.5%. The ADAG formula converts HbA1c to estimated average glucose (eAG): eAG = 28.7 × HbA1c − 46.7 (mg/dL).

<5.7%
Normal
5.7-6.4%
Prediabetes
≥6.5%
Diabetes
<7%
Diabetic target

Sources: ADA, ADAG Study, WHO, CDC.

Key Takeaways

  • • HbA1c <5.7% indicates normal glucose metabolism
  • • Prediabetes (5.7-6.4%) increases diabetes risk; lifestyle changes can prevent progression
  • • eAG helps translate lab results into daily glucose terms (mg/dL or mmol/L)
  • • Target HbA1c <7% for most adults with diabetes per ADA

Did You Know?

🔢 A 1% drop in HbA1c reduces microvascular risk by ~37%
📊 eAG 154 mg/dL = HbA1c 7% (ADA target reference)
💡 HbA1c can be affected by anemia and hemoglobin variants
🌍 ~96 million US adults have prediabetes (CDC)
📈 Red blood cell lifespan (~120 days) determines HbA1c window
🎯 CGM time-in-range correlates with HbA1c for trend assessment

How Does HbA1c Work?

Glycation

Glucose attaches to hemoglobin in red blood cells. Higher average glucose = more glycation = higher HbA1c.

ADAG Formula

eAG (mg/dL) = 28.7 × HbA1c − 46.7. Reverse: HbA1c = (eAG + 46.7) / 28.7.

Clinical Use

Diagnosis, monitoring, and treatment targets. Check every 3-6 months in diabetes.

Expert Tips

Recheck HbA1c every 3 months until target reached
Discuss hemoglobin variants if results seem inconsistent
Use eAG to explain lab results in familiar glucose units
Individualize targets (e.g., <8% for elderly, limited life expectancy)

HbA1c Categories

RangeCategoryeAG (mg/dL)
<5.7%Normal<117
5.7-6.4%Prediabetes117-140
≥6.5%Diabetes≥140
7% (target)Controlled154

Frequently Asked Questions

What is HbA1c?

HbA1c (hemoglobin A1c) measures the percentage of hemoglobin with glucose attached. It reflects your average blood sugar over the past 2-3 months. Normal is below 5.7%, prediabetes 5.7-6.4%, diabetes ≥6.5% per ADA criteria.

How is eAG calculated from HbA1c?

The ADAG formula: eAG (mg/dL) = 28.7 × HbA1c − 46.7. For mmol/L: eAG = 1.59 × HbA1c − 2.59. Example: HbA1c 7% → eAG ≈ 154 mg/dL (8.6 mmol/L).

What is a normal HbA1c range?

Normal: <5.7%. Prediabetes: 5.7-6.4%. Diabetes: ≥6.5%. For diabetics, ADA recommends <7% for most adults, with individualized targets.

How often should HbA1c be checked?

Annually for prediabetics. Every 3 months for diabetics until target reached, then every 6 months. More frequent if treatment changes or goals not met.

Can HbA1c be falsely low or high?

Yes. Anemia, hemoglobin variants, recent blood loss, or kidney disease can affect results. Discuss with your provider if results seem inconsistent with fingerstick readings.

What is the relationship between HbA1c and average glucose?

HbA1c correlates with mean glucose. A 1% change in HbA1c ≈ 29 mg/dL change in average glucose. eAG helps translate lab results into daily glucose terms.

Key Statistics

120
Days RBC lifespan
37%
Microvascular risk reduction per 1% A1c drop
154
eAG at 7% (mg/dL)
96M
US prediabetic adults

Official Data Sources

ADA Standards of Care ↗
Diabetes care standards and HbA1c targets
ADAG Study ↗
HbA1c-eAG conversion formula
CDC Diabetes ↗
US diabetes and prediabetes statistics
WHO Diabetes ↗
Global diabetes guidelines

⚠️ Disclaimer: This calculator is for educational purposes only. It is not a substitute for professional medical advice, diagnosis, or treatment. Always consult a qualified healthcare provider.

👈 START HERE
⬅️Jump in and explore the concept!
AI

Related Calculators

Advanced Warsaw Method Calculator - Diabetes Insulin Dosing

Comprehensive Warsaw Method calculator for Type 1 diabetes management. Calculate insulin doses for high-fat and high-protein meals using Fat-Protein Units...

Health

Advanced Glycemic Load Calculator

Comprehensive glycemic load calculator with advanced meal planning, 5000+ food database, portion optimization, diabetes management integration, personalized...

Health

CVD Risk Calculator - Cardiovascular Disease Risk Assessment

Advanced cardiovascular disease risk calculator with multiple validated models (Framingham, PREVENT, ASCVD, QRISK3), 10-year and 30-year risk projections...

Health

Advanced ABI Calculator (Ankle-Brachial Index)

Comprehensive Ankle-Brachial Index calculator with multiple measurement methods, advanced PAD risk assessment, exercise testing capability, cardiovascular...

Health

AHI Calculator - Apnea-Hypopnea Index

Comprehensive Apnea-Hypopnea Index calculator for sleep apnea diagnosis and severity assessment. Features multiple sleep study indices (AHI, RDI, ODI)...

Health

Advanced Arterial Age Calculator

Comprehensive arterial age calculator with multi-method cardiovascular risk assessment, Agatston calcium score analysis, clinical decision support...

Health