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 source: eAG (mg/dL) = 28.7 × A1C − 46.7, published by the American Diabetes Association based on the ADAG study. This is a population-average relationship — your own glucose meter readings can vary from this estimate. This tool does not diagnose diabetes or prediabetes. See our medical disclaimer.
Understanding A1C, eAG, and blood sugar averages
A1C (also written HbA1c, hemoglobin A1c, or glycated hemoglobin) reflects your average blood glucose over roughly the past 2-3 months, unlike a fingerstick or continuous glucose monitor reading, which shows blood sugar at a single moment. Because A1C is reported as a percentage and most home glucose meters report in mg/dL, clinicians and patients often want to translate between the two — that’s what estimated Average Glucose (eAG) does. This conversion is commonly used alongside diabetes management, prediabetes monitoring, and general metabolic health tracking.
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Frequently asked questions
What’s the difference between A1C and a regular blood sugar reading?
A regular fingerstick or meter reading shows your blood sugar at that exact moment, which can swing significantly based on food, activity, and stress. A1C reflects your average blood glucose over roughly the past 2-3 months, giving a more stable picture of overall control.
What A1C level is considered normal, prediabetic, or diabetic?
Per the American Diabetes Association, an A1C below 5.7% is generally considered normal, 5.7%-6.4% is in the prediabetes range, and 6.5% or above on two separate tests is used to diagnose diabetes. These are general reference ranges — your doctor interprets your result alongside your full health picture.
Why doesn’t my eAG match my glucose meter’s average?
The A1C-to-eAG formula is based on a population-level study (the ADAG study) and represents an average relationship, not a precise 1:1 conversion for every individual. Factors like red blood cell lifespan, certain anemias, and other conditions can cause your personal eAG to differ somewhat from your meter’s actual average.
How often should A1C be checked?
For most people with well-controlled diabetes, every 6 months is typical; for those adjusting treatment or with less stable control, every 3 months is more common. Your doctor will set the right cadence for your situation.