A1C Calculator
Convert A1C to estimated average glucose — and back — with the standard ranges
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Quick summary
Enter your A1C percentage to see your estimated average glucose (eAG) in mg/dL and mmol/L, or switch to convert a glucose reading back to A1C. An A1C of 7% corresponds to an average glucose of about 154 mg/dL (8.6 mmol/L). Ranges follow ADA guidelines: normal below 5.7%, prediabetes 5.7–6.4%, and diabetes 6.5% or higher. This is educational — discuss your numbers with your doctor.
Reviewed by Simple Calculators TeamLast reviewed
For information only — not medical advice. Results are estimates from published formulas and can't account for your health history. Talk to a doctor or other qualified clinician before making health decisions.
How to use this calculator
- Enter the inputs requested by the calculator.
- Choose the units or options that match your situation and review the assumptions.
- Run or update the calculation to see the result.
- Review the result, breakdown, and formulas shown on the page.
- Check the inputs, units, dates, and limitations before saving or sharing the result.
Frequently asked questions
What is A1C and what does it measure?
A1C (also called HbA1c) reflects your average blood glucose over the past 2–3 months, shown as a percentage. It measures how much sugar is attached to your hemoglobin. A higher A1C means higher average glucose. It's the standard test for diagnosing and monitoring diabetes.
How do I convert A1C to average glucose?
Use the ADAG formula: estimated average glucose (mg/dL) = 28.7 × A1C − 46.7. For an A1C of 7%, that's about 154 mg/dL, or 8.6 mmol/L. This calculator applies the formula and also converts a glucose value back to an equivalent A1C.
What A1C is normal, prediabetes, or diabetes?
Per the American Diabetes Association: an A1C below 5.7% is normal, 5.7%–6.4% is prediabetes, and 6.5% or above indicates diabetes. Many people with diabetes aim for an A1C under 7%, but targets are individual — your doctor sets the right goal for you.
Is estimated average glucose the same as a finger-stick reading?
Not exactly. eAG is a long-term average derived from A1C, while a finger-stick or meter reading is a single moment in time that rises and falls with meals and activity. eAG helps you relate your A1C to the daily glucose numbers you see on a meter.
Key terms
- A1C / HbA1c
- Average blood glucose over 2–3 months, as a percentage.
- eAG
- Estimated average glucose derived from A1C.
- ADAG Formula
- eAG (mg/dL) = 28.7 × A1C − 46.7.
- mmol/L
- The glucose unit used outside the US; mg/dL ÷ 18.02.
Methodology, sources & limitations
This page shows the formula, assumptions, and limitations used for this estimate. Rates, thresholds, and other time-sensitive inputs can change, so verify them against the relevant official source before relying on a result.
For our review approach and the primary sources we consult, see the methodology and source policy. If you spot an outdated figure or formula, please contact us with a correction.