A1C Calculator and A1C Levels Chart

Reviewed by the JForH team · 2026-10-30

Multiply your A1C by 28.7 and subtract 46.7 to get your average blood sugar in mg/dL. An A1C of 7% works out to about 154 mg/dL (8.5 mmol/L), and 6% to about 126 mg/dL (7.0 mmol/L). The formula comes from the ADAG study (Nathan et al., Diabetes Care, 2008).

How do I convert my A1C to blood sugar?

Multiply your A1C by 28.7, then subtract 46.7. The answer is your estimated average glucose (eAG) in mg/dL, the same unit your home meter shows.

Say your A1C came back at 8%. That gives 28.7 × 8 − 46.7 = 182.9, so your blood sugar has averaged about 183 mg/dL. Type your number into the calculator on this page, or find it in the chart below.

• In mg/dL (used in the US): eAG = 28.7 × A1C − 46.7
• In mmol/L (used in many other countries): eAG = 1.59 × A1C − 2.59

Both formulas come from the A1C-Derived Average Glucose (ADAG) study. Researchers compared A1C with frequent finger-stick and continuous glucose readings in 507 adults.

The result is an estimate. In that study, two people with the same A1C could have somewhat different true averages. Use it as a guide, not an exact reading.

What does each A1C level mean in blood sugar?

The chart runs from 5% to 12%. Find your A1C in the left column. Next to it is your average blood sugar, rounded to a whole number in mg/dL and to one decimal in mmol/L. Every row uses the ADAG formula.

Here is a quick way to read it. Each 1-point change in A1C is about 29 mg/dL (1.6 mmol/L) of average blood sugar. Going from 9% to 8% means your average fell from about 212 to about 183 mg/dL.

What is a normal A1C?

A normal A1C is below 5.7%. The American Diabetes Association (ADA) and the CDC use these ranges for adults:

The diagnosis is made on the A1C itself. The blood sugar column is worked out with the ADAG formula and is there only to help you picture the number.

What does an A1C test actually measure?

It measures how much sugar has stuck to your red blood cells. More exactly, it is the share of your hemoglobin, the protein in red blood cells that carries oxygen, that has sugar attached.

Red blood cells live for a few months. So A1C reflects your average over roughly the past 3 months, according to the NIDDK. The CDC puts it at the past 2 or 3 months.

You don't need to fast for it. Results come as a percentage, such as 6.8%, and sometimes also in mmol/mol.

Is an A1C of 6.1 prediabetes?

Yes. Any A1C from 5.7% to 6.4% is in the prediabetes range, and 6.1% works out to an average of about 128 mg/dL.

Prediabetes means your sugar is higher than normal but not high enough to be called diabetes. The ADA notes that risk rises across this range and climbs faster near the top. So 6.2% carries more risk than 5.8%.

This is a warning you can act on. Changes to eating, activity and weight can lower the chance of moving on to type 2 diabetes.

What A1C level is diabetes?

An A1C of 6.5% or higher is in the diabetes range. Unless you have clear symptoms of very high blood sugar, the ADA says the result should be confirmed with a second test.

That second test can be a repeat A1C or a different one, such as fasting plasma glucose. One high number on its own doesn't settle it.

What is a good A1C if I have diabetes?

For many adults with diabetes who aren't pregnant, the ADA says below 7% is a fitting goal. That's an average blood sugar of about 154 mg/dL.

Your goal is set with you, person by person. Some people can aim lower if they can get there safely, without low blood sugar. Others are better off with a higher goal.

What A1C is too high?

An A1C is too high when it sits above the goal you and your doctor agreed on. For many adults with diabetes, that means 7% or more.

The higher the A1C, the higher your sugar has been running. At 7.4% your average is about 166 mg/dL. At 9% it is about 212 mg/dL, and at 10% about 240 mg/dL.

A high result is not a judgment on you. It tells you and your care team that the plan needs a change. The ADA suggests rechecking about every 3 months until you are back at goal.

What is a good A1C for a 70-year-old?

It depends on your overall health more than your age. The ADA Standards of Care section on older adults suggests these goals:

Goals are looser for one reason, and that is safety. Low blood sugar can cause falls, confusion and hospital visits, and older adults have more of them. Ask your care team which row fits you.

Why doesn't my A1C match my meter?

Often it's because something has changed how long your red blood cells live. A1C depends on that, so anything that shortens or lengthens their life can make the result read too high or too low. The ADA and NIDDK list:

• Anemia. Iron-deficiency anemia can make A1C read falsely high. Other anemias, such as hemolytic anemia, can also throw it off.
• Kidney failure and dialysis, and treatment with erythropoietin, a medicine that boosts red blood cells.
• Recent blood loss or a blood transfusion.
• Pregnancy, because red blood cells turn over faster. A1C is not used to diagnose diabetes that starts in pregnancy.
• Some hemoglobin variants, such as sickle cell trait or thalassemia. These are more common in people of African, Mediterranean or Southeast Asian ancestry, and with some lab methods they can affect results. A1C cannot be used at all in people with sickle cell disease.
• Liver disease.

A meter can also miss highs or lows if you always check at the same times of day. If the numbers don't line up, tell your doctor. A fasting glucose test or a continuous glucose monitor (CGM) can give a clearer picture.

Is GMI the same as A1C?

No. GMI, the Glucose Management Indicator on a CGM report, estimates your A1C from sensor readings. A1C is a lab blood test.

A CGM is a small sensor worn on the skin that checks your sugar every few minutes. GMI works the opposite way from eAG. It starts with your average sensor glucose and estimates the A1C that goes with it.

The formula, from Bergenstal and colleagues (Diabetes Care, 2018), is GMI (%) = 3.31 + 0.02392 × average glucose in mg/dL. A sensor average of 154 mg/dL gives a GMI of about 7.0%. The ADA suggests using about 14 days of CGM data for these reports.

GMI and a lab A1C often differ by a few tenths of a point, and sometimes more. That doesn't mean either one is wrong. The ADA describes GMI as an approximation of A1C that is not always equivalent.

A CGM also shows what A1C can't, such as time in range (the share of the day spent between 70 and 180 mg/dL), lows overnight and spikes after meals. For many adults with diabetes, the goal is more than 70% time in range, per the International Consensus on Time in Range and the ADA.

How often should I get my A1C checked?

At least twice a year if you have diabetes and are meeting your goal, the ADA says. Test more often, such as every 3 months, if you're not at goal or your treatment recently changed.

If you don't have diabetes, you'll be screened less often. The CDC suggests an A1C test for adults over 45, and for younger adults with overweight and another risk factor.

What should I do with my A1C result?

• Below 5.7%: keep up your healthy habits and follow your doctor's screening schedule.
• 5.7% to 6.4%: ask about a lifestyle program for prediabetes and when to recheck.
• 6.5% or higher, with no diagnosis yet: see your doctor to confirm the result with a second test.
• Already living with diabetes: compare your A1C with the goal you set with your care team. Then look at your daily readings or CGM report for patterns, such as high mornings or spikes after dinner.

This calculator is for education. It does not diagnose diabetes or replace advice from your doctor.

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Last updated: 2026-10-30. Educational information, not medical advice. Talk to your doctor before changing your treatment.