Two numbers for the same blood sugar
Your A1C test reports the percentage of hemoglobin carrying glucose — a roughly three-month average — while glucose meters and labs report sugar levels in mg/dL (or mmol/L outside the US). The American Diabetes Association's ADAG study pinned down the relationship between the two, and this calculator converts in both directions with those published equations, so a lab A1C and a meter average stop being two different languages.
Equations from the ADAG (A1C-Derived Average Glucose) study used by the ADA. Averages hide swings: two people with the same A1C can have very different daily highs and lows.
Where a result falls
The ADA's reference ranges for A1C are: below 5.7% — normal; 5.7–6.4% — prediabetes; 6.5% or above — diabetes (diagnosis is confirmed with repeat testing). Many adults with diabetes aim for an A1C under 7%, but targets are individual — age, other conditions and hypoglycemia risk all move the goal, and only your care team can set yours.
Worked example
An A1C of 7.0% converts to an estimated average glucose of 154 mg/dL (28.7 × 7.0 − 46.7 = 154.2), which is 8.5 mmol/L by the ADAG mmol/L equation. Working backwards, a meter average of 154 mg/dL corresponds to an A1C of about 7.0%.
How to use this calculator
- Pick the direction: A1C to average glucose, or a glucose average back to A1C.
- Enter your value — for the glucose direction, an average of many readings (fasting alone will skew low).
- Read the conversion and where it sits against the reference ranges.
- Bring the printout to your appointment if the two numbers ever disagree — anemia, pregnancy and some conditions distort A1C.
Not medical advice. This page converts numbers with the standard published formulas; it does not diagnose anything. Diabetes diagnosis and treatment decisions belong to your clinician, using lab testing.