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A1C to Average Glucose Calculator

Turn your HbA1c into average blood glucose

How it is calculated

The tool converts an HbA1c percentage into an estimated average glucose (eAG) with the ADAG linear equation: eAG (mg/dL) = 28.7 × A1C − 46.7. The mmol/L value is that figure divided by 18: eAG (mmol/L) = eAG (mg/dL) ÷ 18. A1C is entered as a percent (for example 7 for 7%), not as the newer mmol/mol unit. Both results are rounded to one decimal. Any value above zero is accepted, even ones that are not physiologically realistic, so there is no warning for extreme inputs. The estimate is an average over about three months and does not show daily highs and lows. Meters and labs may differ slightly, and it is not a diagnosis.

Worked example

HbA1c 7%. Multiply: 28.7 × 7 = 200.9. Subtract: 200.9 − 46.7 = 154.2, so 154.2 mg/dL. Divide by 18: 154.2 ÷ 18 = 8.57, shown as 8.6 mmol/L. An A1C of 7% therefore corresponds to an average glucose of about 154 mg/dL.

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Common mistakes

  • Entering the A1C in mmol/mol (for example 53) instead of percent. The equation expects percent; 53 would give an absurd 1,474.4 mg/dL.
  • Treating eAG as the reading you should see on your meter at any time. It is a three-month average, and individual readings can be far above or below it.
  • Entering the A1C as a decimal fraction such as 0.07. Type 7 for 7%.
  • Mixing up mg/dL and mmol/L when comparing with a meter. Check which unit your meter shows before comparing it with the value here.

About this calculator

This calculator converts an HbA1c percentage into estimated average glucose (eAG) using the regression equation from the 2008 ADAG (A1c-Derived Average Glucose) study: eAG (mg/dL) = 28.7 × A1C − 46.7, or eAG (mmol/L) = 1.59 × A1C − 2.59. The study measured continuous glucose over three months in over 500 people and correlated it directly to their lab A1c.

Endocrinologists and diabetes educators use eAG to translate the abstract A1c percentage into the same mg/dL or mmol/L units patients see on their glucose meter, making it easier to connect long-term control to day-to-day readings. It's the same conversion many glucose meters and lab reports now print alongside the A1c result.

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