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).
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⚠️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).
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?
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
HbA1c Categories
| Range | Category | eAG (mg/dL) |
|---|---|---|
| <5.7% | Normal | <117 |
| 5.7-6.4% | Prediabetes | 117-140 |
| ≥6.5% | Diabetes | ≥140 |
| 7% (target) | Controlled | 154 |
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
Official Data Sources
⚠️ 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.