A1C to Estimated Average Glucose (eAG) Calculator

Hemoglobin A1c (HbA1c) measures the percentage of red blood cells that have sugar-coated hemoglobin. It provides a 2-3 month average of your blood glucose levels. Translating this percentage into an Estimated Average Glucose (eAG) in mg/dL or mmol/L helps conceptualize what that percentage means on a daily basis.

The Math (Manual Calculation)

If you prefer to calculate this manually, the formula validated by the ADAG study group is:

• eAG (mg/dL) = (28.7 × A1C) - 46.7
• eAG (mmol/L) = eAG (mg/dL) / 18.015

Why It Matters

An A1C of 7.0% corresponds to an average glucose of 154 mg/dL. By understanding this translation, patients can better align their daily CGM data with their quarterly lab results. If your CGM average is 120 mg/dL but your lab A1C comes back at 8.0% (eAG 183 mg/dL), it indicates unmeasured spikes, likely after meals. Read our Nutrition Guide for strategies to flatten postprandial spikes.

Common Mistakes

• Assuming A1C tells the whole story: A1C is an average. An A1C of 7.0% could mean blood sugars are steady at 154 mg/dL, or it could mean violent swings between 40 mg/dL and 300 mg/dL. Continuous Glucose Monitors measure Time in Range (TIR), a superior metric for glycemic variability.
• Falsely altered A1C: Conditions affecting red blood cell lifespan (anemia, recent blood loss, variants in hemoglobin traits) can artificially raise or lower A1C results.

Frequently Asked Questions (FAQ)

What is a normal A1C?

A normal A1C in someone without diabetes is below 5.7%. The ADA target for non-pregnant adults with diabetes is generally < 7.0%.