Health

A1C Calculator

Convert A1C to estimated average glucose (eAG) in mg/dL and mmol/L, or work backward from average glucose to A1C.

A1C Calculator

Conversion Direction

A1C (%)

Method

How this calculator works

eAG (mg/dL) = 28.7 × A1C − 46.7; eAG (mmol/L) = eAG_mgdl / 18.0182. Reverse: A1C (%) = (eAG_mgdl + 46.7) / 28.7.

Choose whether you want to convert from A1C to average glucose, or from average glucose to A1C.
For A1C → eAG: multiply your A1C percent by 28.7 and subtract 46.7 to get mg/dL.
Divide the mg/dL result by 18.0182 to also see it in mmol/L.
For eAG → A1C: add 46.7 to your average glucose in mg/dL and divide by 28.7.

Examples

Worked examples

Real numbers, end-to-end results.

A1C = 7.0%

eAG ≈ 154 mg/dL (8.6 mmol/L)

28.7 × 7.0 − 46.7 = 154.2 mg/dL; ÷ 18.0182 = 8.56 mmol/L.

A1C = 5.5%

eAG ≈ 111 mg/dL (6.2 mmol/L)

A normal-range A1C corresponds to an average glucose just above 110 mg/dL.

Average glucose = 183 mg/dL

A1C ≈ 8.0%

(183 + 46.7) / 28.7 = 8.0%.

Use cases

When to use it

Understanding lab A1C results in everyday glucose-meter units.
Setting and tracking personal blood-sugar targets with your care team.
Comparing meter or CGM averages against your reported A1C.
Explaining diabetes and prediabetes thresholds to patients or students.

Disclaimer: This calculator provides estimates for informational and educational purposes only. It is not a substitute for professional medical advice, diagnosis, or treatment. Always consult a qualified healthcare provider for decisions affecting your health. Results depend on the accuracy of inputs provided.

FAQ

Frequently asked questions

What is A1C and what does it tell me?

A1C (also called HbA1c or glycated hemoglobin) reflects your average blood sugar over roughly the past 2–3 months. Because red blood cells live about three months, the percentage of hemoglobin coated with glucose gives a stable, long-term picture of glucose control—unlike a single finger-stick reading.

What is eAG and how does it relate to A1C?

eAG (estimated average glucose) translates your A1C percentage into the same mg/dL or mmol/L units you see on a glucose meter, making the number easier to relate to daily readings. The ADA formula is eAG (mg/dL) = 28.7 × A1C − 46.7.

What A1C level indicates diabetes?

By ADA criteria, an A1C below 5.7% is normal, 5.7% to 6.4% indicates prediabetes, and 6.5% or higher on two tests indicates diabetes. Many people with diabetes aim for a personal target under 7%, but goals should be set with your doctor.

How do I convert eAG back to A1C?

Rearrange the ADA formula: A1C (%) = (eAG_mgdl + 46.7) / 28.7. This calculator does it both ways—enter an A1C to get eAG, or enter an average glucose to estimate the corresponding A1C.

Why might my A1C and meter averages disagree?

A1C is an estimate. Conditions such as anemia, recent blood loss, pregnancy, certain hemoglobin variants, and kidney disease can shift A1C away from your true average glucose. If the two disagree consistently, discuss it with your healthcare provider.