A1C calculator
Convert an A1C result to estimated average glucose, or average glucose back to A1C.
How this works, sources, and questions
How it works
Alma uses the ADAG study regression that the American Diabetes Association uses for estimated average glucose: eAG in mg/dL = 28.7 x A1C - 46.7, and eAG in mmol/L = 1.59 x A1C - 2.59. Going the other way, Alma solves the same equation for A1C. The result is placed in the CDC A1C ranges: normal below 5.7%, prediabetes 5.7% to 6.4%, and diabetes 6.5% or above.
Evidence
The ADAG study fit the equation to about 2,700 glucose readings per person over 3 months, and it held across age, sex, diabetes type, and race or ethnicity. It is an average: a given A1C can sit alongside a real average glucose about 15.7 mg/dL higher or lower, and it hides spikes and lows. Anemia, pregnancy, kidney disease, and some hemoglobin variants can also shift A1C. A diagnosis needs a lab test read by a clinician.
- Nathan and colleagues (ADAG study): Translating the A1C assay into estimated average glucose values
- American Diabetes Association: eAG/A1C conversion calculator
- CDC: A1C test for diabetes and prediabetes
Updated
Common questions
What is A1C?
A1C is the share of your hemoglobin with glucose attached. Because red blood cells live about 3 months, it reflects your average blood sugar over the past 2 to 3 months, not a single day.
What does an A1C of 7% mean in average glucose?
About 154 mg/dL, or 8.6 mmol/L in the ADA table. The CDC says the A1C goal for most people with diabetes is 7% or less, and your clinician sets your own goal from your full history.
What A1C is normal?
The CDC lists below 5.7% as normal, 5.7% to 6.4% as prediabetes, and 6.5% or above as diabetes. These ranges are used with a lab test, not a home estimate.
Why does my meter average differ from my A1C estimate?
Finger sticks catch moments, often before meals, while A1C reflects all hours including overnight. Red blood cell lifespan, anemia, and pregnancy can also move A1C. Bring both numbers to your clinician.
Can food change my A1C?
What you eat affects blood sugar, and A1C reflects about 3 months of it. Talk with your clinician before changing medication or making big diet changes, especially if you take insulin or drugs that can cause lows.