Convert between A1C (a 2-3 month average blood sugar measure) and estimated Average Glucose (eAG, in the same units your glucose meter uses) using the ADA-published conversion formula. This is a unit conversion, not a new lab result — talk to your doctor about what your actual A1C means for your care plan.
Formula used: estimated average glucose (mg/dL) = 28.7 × A1C − 46.7, from the A1C-Derived Average Glucose (ADAG) study. To convert mg/dL to mmol/L, divide by 18. This is an estimate for education, not a diagnosis. See our medical disclaimer.
What A1C and estimated average glucose mean
Glucose in your blood sticks to hemoglobin, the protein inside red blood cells. Red blood cells live for roughly three months, so the share of hemoglobin carrying glucose, your A1C, reflects your average blood sugar over the previous two to three months. Estimated average glucose (eAG) translates that percentage into the same units your glucose meter uses, which makes the number easier to relate to your daily readings.
A1C to eAG conversion chart
| A1C | eAG (mg/dL) | eAG (mmol/L) |
|---|---|---|
| 5% | 97 | 5.4 |
| 5.7% | 117 | 6.5 |
| 6% | 126 | 7.0 |
| 6.5% | 140 | 7.8 |
| 7% | 154 | 8.6 |
| 8% | 183 | 10.2 |
| 9% | 212 | 11.8 |
| 10% | 240 | 13.3 |
| 11% | 269 | 14.9 |
| 12% | 298 | 16.6 |
What your A1C range means
The American Diabetes Association uses these A1C ranges for diagnosis in adults who are not pregnant:
- Below 5.7%: normal
- 5.7% to 6.4%: prediabetes, meaning higher-than-normal blood sugar and increased risk of type 2 diabetes
- 6.5% or higher: diabetes, usually confirmed by a repeat test unless symptoms make the diagnosis clear
For people who already have diabetes, a common target is an A1C below 7%, which is an eAG of about 154 mg/dL. Targets are personal. Doctors often set a looser goal, such as below 8%, for older adults or people prone to low blood sugar, and a tighter goal for some younger people when it can be reached safely.
When A1C can be misleading
Because A1C depends on red blood cells, anything that changes how long they live can skew the result:
- Falsely low: recent blood loss or transfusion, hemolytic anemia, pregnancy, and some chronic kidney disease treatments such as erythropoietin
- Falsely high: iron-deficiency anemia, and sometimes advanced kidney disease
- Either direction: some hemoglobin variants, such as sickle cell trait, with certain lab methods
A1C also hides swings. Two people with an A1C of 7% can have very different days if one runs steady and the other alternates between highs and lows. That is why continuous glucose monitors report “time in range” and a glucose management indicator (GMI), which is similar to eAG but calculated from sensor data. Your GMI and lab A1C often differ by a few tenths of a percent, and that is normal.
Lowering a high A1C
Every 1-point drop in A1C lowers the risk of eye, kidney and nerve complications. The main levers are nutrition, physical activity, weight loss when appropriate, and medicines. Medicine options range from metformin to GLP-1 receptor agonists, SGLT2 inhibitors and insulin. Our comparisons below explain how the common ones differ.
Related reading
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- Mounjaro vs Trulicity
- Invokana vs Jardiance
- Humalog vs Novolog
- Tresiba vs Levemir
- Metformin and alcohol
Frequently asked questions
What is a normal A1C?
Below 5.7% is considered normal. From 5.7% to 6.4% is prediabetes, and 6.5% or higher on two tests indicates diabetes.
What blood sugar does an A1C of 7 equal?
An A1C of 7% corresponds to an estimated average glucose of about 154 mg/dL, or 8.6 mmol/L.
How often should A1C be checked?
The ADA suggests at least twice a year when diabetes is stable and at target, and about every three months when treatment changes or targets are not being met.
Why does my meter average not match my eAG?
Finger-stick checks usually happen at certain times, such as before meals, and miss the highs after eating and the lows overnight. A1C reflects every hour of the day, so the two averages often differ.
Sources
- Nathan DM, et al. Translating the A1C assay into estimated average glucose values. Diabetes Care. 2008. PubMed
- American Diabetes Association. Standards of Care in Diabetes
- The A1C test and diabetes. National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK)
About this article
Written by the Health Linear Editorial Team from primary sources such as FDA prescribing information, DailyMed, NIH and peer-reviewed studies, which are linked in the article. Last updated October 27, 2026.
Read our editorial process and medical disclaimer. Spotted an error? Tell us and we will correct it.