Blood sugar converter
A1C to average glucose calculator
Your A1C is a percentage. Your glucose meter shows mg/dL. This converter links the two with the formula from the study labs use, and shows where your A1C falls.
Convert
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What you will see
The matching average glucose (or A1C) and which A1C range it falls in.
Educational only, not medical advice. A converter cannot diagnose diabetes.
Source
ADAG study: Nathan DM et al., Diabetes Care 2008. Ranges: ADA Standards of Care 2026 and CDC.
Validated in
507 adults (268 with type 1 diabetes, 159 with type 2 diabetes and 80 without diabetes) who wore glucose monitors and had A1C tests over about 3 months.
Limits
An average for groups, with a wide spread for each person. Not for pregnancy, children, or conditions that make A1C inaccurate such as anemia, kidney failure or blood disorders.
The A1C chart
Each row uses the ADAG formula (Nathan 2008). The ranges are the diagnostic ranges from the ADA and CDC (ADA Standards 2026) (CDC).
| A1C | Average glucose (mg/dL) | Average glucose (mmol/L) | Range |
|---|---|---|---|
| 5% | 97 | 5.4 | Normal range |
| 5.5% | 111 | 6.2 | Normal range |
| 5.7% | 117 | 6.5 | Prediabetes range |
| 6% | 126 | 7.0 | Prediabetes range |
| 6.5% | 140 | 7.8 | Diabetes range |
| 7% | 154 | 8.6 | Diabetes range |
| 7.5% | 169 | 9.4 | Diabetes range |
| 8% | 183 | 10.2 | Diabetes range |
| 8.5% | 197 | 10.9 | Diabetes range |
| 9% | 212 | 11.7 | Diabetes range |
| 10% | 240 | 13.3 | Diabetes range |
| 11% | 269 | 14.9 | Diabetes range |
| 12% | 298 | 16.5 | Diabetes range |
Where the formula comes from
A1C measures how much glucose is stuck to red blood cells, which reflects blood sugar over roughly the past 3 months (CDC). To turn it into the units of a glucose meter, the A1C-Derived Average Glucose (ADAG) study followed 507 adults with type 1 diabetes, type 2 diabetes or no diabetes. It compared their A1C with thousands of glucose readings from continuous monitors and finger sticks (Nathan 2008).
The best fit was a straight line: average glucose in mg/dL equals 28.7 times A1C minus 46.7, which explained most of the variation (R² 0.84) (Nathan 2008). Labs that report "eAG" next to your A1C use this formula.
Why your meter average may not match
The formula gives the average for people with a given A1C, and individuals vary around it. In the study, an A1C of 7% matched an average glucose of 154 mg/dL, but the 95% range ran from 123 to 185 mg/dL (Nathan 2008). At 6% it was 126 mg/dL (100 to 152) and at 8% it was 183 mg/dL (147 to 217) (Nathan 2008).
A1C can also be off because of the blood, not the sugar. CDC lists severe anemia, kidney failure, liver disease, blood disorders such as sickle cell anemia or thalassemia, some medicines, blood loss or transfusion, and early or late pregnancy as things that can falsely raise or lower it (CDC). If your A1C and your meter tell different stories, show both to your clinician.
A1C ranges
Below 5.7% is the normal range, 5.7% to 6.4% is prediabetes, and 6.5% or higher is diabetes (CDC). A diagnosis usually needs two abnormal results (ADA Standards 2026). More detail, including fasting glucose and glucose tolerance test ranges, is on our prediabetes page.
Common questions
What average blood sugar is an A1C of 6.5?
About 140 mg/dL (7.8 mmol/L), using the ADAG formula (Nathan 2008). An A1C of 6.5% is the lower edge of the diabetes range (CDC).
What A1C is an average glucose of 100?
About 5.1%, which is in the normal range (Nathan 2008) (CDC).
Is this the same as the GMI on my glucose sensor?
No. GMI (glucose management indicator) runs the conversion the other way, from sensor glucose to an A1C-like number, with a different formula (Bergenstal 2018). Both are estimates; your lab A1C is the measured value.
Not sure about your diabetes risk? Take the diabetes risk test.
Sources
- Nathan DM, Kuenen J, Borg R, et al. Translating the A1C assay into estimated average glucose values. Diabetes Care. 2008;31(8):1473-1478. doi.org/10.2337/dc08-0545
- American Diabetes Association Professional Practice Committee. 2. Diagnosis and Classification of Diabetes: Standards of Care in Diabetes 2026. Diabetes Care. 2026;49(Suppl 1):S27-S49. doi.org/10.2337/dc26-S002
- Centers for Disease Control and Prevention. A1C Test for Diabetes and Prediabetes. www.cdc.gov/diabetes/diabetes-testing/prediabetes-a1c-test.html
- Bergenstal RM, Beck RW, Close KL, et al. Glucose Management Indicator (GMI): A New Term for Estimating A1C From Continuous Glucose Monitoring. Diabetes Care. 2018;41(11):2275-2280. doi.org/10.2337/dc18-1581
Written and maintained by the uncovermyrisk.com editorial team. We do not have a medical reviewer; every claim links to its primary source above. Last reviewed: 2026-10-27. Spotted an error? See About.