A1C to Glucose Calculator
Convert A1C to estimated average glucose and back.
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This calculator provides estimates based on population research. Results are not medical advice. Consult a qualified healthcare provider before making health or nutrition decisions.
How it works
The A1C to glucose calculator translates between two ways of describing long-term blood sugar control: the A1C percentage that laboratories report and the estimated average glucose, or eAG, expressed in the same mg/dL units as a everyday glucose meter. Using the formula from the international ADAG study, it converts an A1C reading into the average glucose it corresponds to, or works backward from an average glucose to the equivalent A1C. This helps people with diabetes make sense of their lab results, because an A1C of 7 percent, for instance, corresponds to an estimated average glucose of about 154 mg/dL, a number that is far easier to relate to daily meter readings. The A1C reflects roughly the previous two to three months of blood sugar, since it measures the fraction of haemoglobin that has become glycated, so it smooths out day-to-day swings that a single finger-stick captures. Clinicians use A1C to diagnose and monitor diabetes and to set treatment targets, while the eAG gives patients an intuitive companion figure. This tool is for educational estimation only and does not replace laboratory testing or medical advice; always discuss your results with a healthcare professional. Enter an A1C percentage or an average glucose to see the conversion.
eAG (mg/dL) = 28.7 × A1C − 46.7
The A1C test reflects average blood sugar over roughly the past three months, and the ADAG study established a linear relationship converting the A1C percentage into an estimated average glucose in mg/dL: multiply the A1C by 28.7 and subtract 46.7. Reversing the equation converts a known average glucose back into an equivalent A1C by adding 46.7 and dividing by 28.7, letting you move between the two scales patients and clinicians use.
Source:ADAG study (Nathan et al., 2008), American Diabetes Association
We review all our tools from time to time to ensure accuracy.
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How to use this calculator
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Enter your values
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Adjust the options
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Frequently asked questions
What is A1C?
A1C, also called glycated haemoglobin or HbA1c, is a blood test that reflects your average blood sugar over roughly the past two to three months. It measures the percentage of haemoglobin in your red blood cells that has sugar attached. Because red cells live about three months, A1C smooths out daily fluctuations and gives a longer-term picture of blood glucose control than a single reading.
What is estimated average glucose?
Estimated average glucose, or eAG, translates the A1C percentage into the same units as a home glucose meter, milligrams per decilitre, so it is easier to interpret. It is calculated from A1C using the ADAG study formula. An eAG of 154 mg/dL, for example, corresponds to an A1C of 7 percent, giving patients a familiar number to relate their long-term control to daily readings.
How accurate is the A1C to glucose conversion?
The conversion is based on a large international study and works well on average, but individual results can vary. Factors such as anaemia, certain haemoglobin variants, pregnancy, and red blood cell lifespan can make a person's actual average glucose differ from the estimate. Treat the converted value as a helpful approximation for understanding trends, not an exact measurement, and rely on laboratory tests for clinical decisions.
What A1C level indicates diabetes?
In general clinical guidelines, an A1C below 5.7 percent is considered normal, 5.7 to 6.4 percent indicates prediabetes, and 6.5 percent or higher on two tests indicates diabetes. Many people with diabetes aim for a target around 7 percent, though goals are individualised. This calculator only converts values and does not diagnose; interpretation and diagnosis should come from a healthcare provider.
Can I convert average glucose back to A1C?
Yes. Select the average glucose option and enter a value in mg/dL, and the calculator applies the ADAG formula in reverse by adding 46.7 and dividing by 28.7 to give the equivalent A1C percentage. This is useful if you track daily meter averages and want to estimate what A1C they might correspond to, though only a lab test measures true A1C.