A1C Calculator
Convert an A1C percentage to estimated average blood glucose, or average glucose back to A1C.
How to use the A1C Calculator
- Choose the convert.
- Enter the a1c.
- Enter the average glucose.
- Choose the glucose unit.
- Press Calculate. The result updates automatically as you type.
About the A1C Calculator
The A1C test measures the percentage of hemoglobin in red blood cells that has glucose attached, which reflects average blood sugar over roughly the previous two to three months. The A1C-Derived Average Glucose (ADAG) study linked A1C to continuous glucose readings, giving the linear formula used here.
Diagnostic thresholds used by the American Diabetes Association are below 5.7% normal, 5.7–6.4% prediabetes and 6.5% or higher diabetes (confirmed by repeat testing). Anemia, recent blood loss, pregnancy, kidney disease and some hemoglobin variants can make A1C less reliable. Individual targets should be set with your healthcare provider.
Results are estimates for general information only and are not medical advice. Talk to a doctor or registered dietitian before making major changes.
Formula
eAG (mg/dL) = 28.7 × A1C − 46.7
eAG (mmol/L) = eAG (mg/dL) ÷ 18.016
A1C = (eAG + 46.7) ÷ 28.7
IFCC (mmol/mol) = (A1C − 2.15) × 10.929
Example calculation
Using the default values:
- Convert = A1C → average glucose
- A1C = 6.5%
the calculator returns:
- Estimated average glucose: 140 mg/dL
- Estimated average glucose (mmol/L): 7.8 mmol/L
- A1C: 6.5%
- A1C (IFCC units): 48 mmol/mol
- A1C range: 6.5% or above – diabetes range
Frequently asked questions
What average blood sugar is an A1C of 7%?
About 154 mg/dL (8.6 mmol/L).
What is a normal A1C?
Below 5.7% for people without diabetes. Many adults with diabetes aim for below 7%, though targets vary by person.
Why doesn't my meter average match my eAG?
Fingerstick averages often over-represent fasting or pre-meal readings and miss overnight and after-meal values, so they can differ from the A1C-based estimate.
Last updated: · Category: Health & Fitness calculators