A1C Calculator
Convert your A1C to estimated average glucose (eAG) and back — in mg/dL or mmol/L — using the ADA’s standard formula.
This calculator is for general information only and is not medical advice or a diagnosis. The estimated average glucose (eAG) is a statistical estimate and may differ from your day-to-day readings. Always discuss your A1C and treatment with your doctor.
How the A1C calculator works
Your A1C (also called HbA1c) reflects your average blood sugar over the past two to three months. This calculator converts that percentage into an estimated average glucose (eAG) — the same units you see on a home glucose meter — and back again. It uses the formula published with the American Diabetes Association’s ADAG study, so the result lines up with the values clinicians use.
eAG (mg/dL) = 28.7 × A1C − 46.7 · mmol/L = mg/dL ÷ 18.0182
For example, an A1C of 7% works out to 28.7 × 7 − 46.7 = 154 mg/dL (8.6 mmol/L). Switch to the “Glucose → A1C” tab to go the other way: enter an average glucose in mg/dL or mmol/L and the tool returns the matching A1C using A1C = (eAG + 46.7) ÷ 28.7.
A1C to average glucose chart
| A1C | eAG (mg/dL) | eAG (mmol/L) |
|---|---|---|
| 5% | 97 | 5.4 |
| 6% | 126 | 7.0 |
| 6.5% | 140 | 7.8 |
| 7% | 154 | 8.6 |
| 8% | 183 | 10.1 |
| 9% | 212 | 11.8 |
| 10% | 240 | 13.4 |
Remember that eAG is an average. Real readings rise and fall around it across the day, and conditions such as anemia or pregnancy can change how A1C relates to actual glucose. Use this number to understand the big picture, and review your target with your doctor.
Frequently asked questions
How do you calculate your A1C?
A1C is measured by a lab blood test, but you can estimate it from your average glucose with the ADA/ADAG formula: A1C = (eAG + 46.7) ÷ 28.7, where eAG is your average glucose in mg/dL. Going the other way, eAG (mg/dL) = 28.7 × A1C − 46.7. For example, an A1C of 7% works out to 154 mg/dL.
What is my A1C if my blood sugar is 140?
Using A1C = (eAG + 46.7) ÷ 28.7, an average glucose of 140 mg/dL is about 6.5%. Note that 140 mg/dL has to be your average over roughly 2–3 months, not a single reading — a one-off 140 doesn’t set your A1C.
What is a good A1C by age?
Targets are individual, but as a general guide the ADA considers below 5.7% normal, 5.7–6.4% prediabetes, and 6.5% or higher the diabetes range. Many adults with diabetes aim for under 7%, while a higher target (for example under 8%) is sometimes set for older adults or people with other health conditions. Your doctor sets the right number for your age and situation.
Can walking 30 minutes a day lower A1C?
Regular activity such as a daily 30-minute walk can help lower average glucose and, over time, A1C for many people — alongside diet, medication and your care plan. This tool only converts A1C to and from average glucose; it does not track activity. Ask your doctor about a plan that fits you.
Why does my eAG differ from my meter readings?
A1C reflects your average glucose over about 2–3 months, so eAG is an average — not a prediction of any single reading. Day-to-day values swing above and below it, and factors like anemia or pregnancy can also affect how A1C relates to actual glucose.