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A1C to average glucose calculator

Reviewed by

Dr. Maria Gutierrez Horn Dr. Maria Gutierrez Horn, MD, FACEAdvisory Board, Endocrinology, Insyght Health
PublishedSeptember 28, 2026Last updatedSeptember 28, 2026
Input: A1C or average glucoseOutput: eAG in mg/dL and mmol/LEstimate, not a diagnosis

Your A1C is a three-month average of your blood sugar, written as a percentage. This calculator turns it into the number you see on a glucose meter, and back again. Enter one value and get the other in seconds.

Enter an A1C between 4.0% and 15.0%.

Don't know your A1C? It's included in every Insyght draw.

This estimate is for education only. It isn't a diagnosis and doesn't replace a lab A1C test.

A1C to average glucose chart

A1CAverage glucose (mg/dL)Average glucose (mmol/L)
5.0%975.4
5.7%1176.5
6.0%1267.0
6.5%1407.8
7.0%1548.5
8.0%18310.1
9.0%21211.7
10.0%24013.3

What can affect your A1C

A1C assumes your red blood cells live about three months. Anything that changes that lifespan can move the number without changing your real blood sugar.

That's why Insyght reads A1C alongside glucose, fasting insulin, ferritin and your full blood count.

Frequently asked questions

What is a normal A1C?
Below 5.7% is normal. 5.7% to 6.4% is the prediabetes range, and 6.5% or higher on two tests indicates diabetes.
What is estimated average glucose (eAG)?
eAG translates your A1C into mg/dL or mmol/L, the same units as a finger-stick or CGM reading.
Is eAG the same as GMI?
No. eAG comes from a lab A1C, while GMI comes from CGM data. If you wear a sensor, use the GMI to A1C calculator.
Can my A1C be normal and still be a problem?
Yes. Insulin often rises years before A1C moves. A fasting insulin test can catch that early shift.
Do I need to fast for an A1C test?
No, A1C doesn't need fasting. Insyght still asks for an 8 to 12 hour fast because glucose, insulin and lipids do.
Your A1C is one number. Your metabolism is a system.

Insyght measures A1C, fasting glucose, fasting insulin, triglycerides and 100+ more data points in one draw, reviewed by a physician against optimal ranges. $199 a year.

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