A1C Calculator
Free A1C calculator. Convert between A1C and average blood glucose (eAG). Check diabetes risk categories and understand your 3-month blood sugar average.
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Last updated: January 2026
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Frequently Asked Questions
What is A1C and what does it measure?
A1C (HbA1c) measures the percentage of hemoglobin with attached glucose, reflecting your average blood sugar over 2-3 months. Unlike daily glucose tests, A1C shows long-term blood sugar control. Normal is below 5.7%, prediabetes is 5.7-6.4%, and diabetes is 6.5% or higher.
How do I convert A1C to average blood glucose?
Use the formula: eAG (mg/dL) = (28.7 × A1C) - 46.7. For example, A1C of 7% equals approximately 154 mg/dL average glucose. For mmol/L, divide by 18. An A1C of 6% ≈ 126 mg/dL, 8% ≈ 183 mg/dL, 9% ≈ 212 mg/dL.
What A1C level should I aim for?
Most adults with diabetes target A1C below 7%. Younger, healthier individuals may aim for 6.5%. Older adults or those with complications may have less strict targets (7.5-8%). Your doctor sets your personal goal based on age, health conditions, and hypoglycemia risk.
How often should A1C be tested?
Test A1C every 3 months if you have diabetes or are adjusting treatment. If blood sugar is stable and well-controlled, testing every 6 months may suffice. Prediabetics should test annually. A1C complements daily glucose monitoring—it doesn't replace it.
Can A1C results be inaccurate?
Yes. Conditions affecting red blood cells can skew results: anemia, kidney disease, recent blood loss, hemoglobin variants, and pregnancy. Very high or low blood sugar swings may give a misleadingly 'normal' A1C. Some ethnicities have naturally higher or lower A1C. Discuss anomalies with your doctor.