How to Calculate A1C From Glucose

If you are actively monitoring your blood sugar with a standard meter or a Continuous Glucose Monitor (CGM), you might be wondering exactly how to calculate A1C from glucose readings between your doctor visits. Understanding the math behind this conversion is an excellent way to track your metabolic health.

The Official A1C Calculation Formula

In a clinical laboratory, an A1C test directly measures the percentage of glycated hemoglobin in your blood. However, if you want to know how to calculate A1C from blood sugar at home, the medical community uses the internationally recognized A1c-Derived Average Glucose (ADAG) formula.

The standard A1C calculation formula works by taking your estimated average glucose (eAG) over a 90-day period. For readings in mg/dL, the formula is: A1C = (eAG + 46.7) ÷ 28.7. This equation provides a highly accurate estimate of what your lab results might look like.

Automating the Math

If you are looking for how to calculate A1C without doing the manual algebra, the easiest method is to use a digital tool. Navigate to our official A1C Calculator, enter your 90-day average blood sugar, and let the engine process the ADAG formula for you instantly. Please note: Mathematical estimates should never replace official laboratory testing or professional medical advice.