About the A1C Calculator
The A1C blood test, also called HbA1c, shows your average blood sugar over the past two to three months. It is reported as a percentage, as mmol/mol in many countries, and as an estimated average glucose (eAG) that matches the units on a home glucose meter. This calculator converts between all of them using the formula from the ADAG study: eAG in mg/dL is 28.7 times the A1C minus 46.7. You can start from any of the four values and it fills in the others, then tells you which range the A1C falls into. It is meant for understanding your results, not for diagnosis, which needs a doctor.
Updated October 2026
How to use the A1C Calculator
- 1Choose the value you have: A1C percent, A1C in mmol/mol, average glucose in mg/dL or in mmol/L.
- 2Type the number.
- 3Read the A1C and the estimated average glucose.
- 4Check the mmol/mol value and the range.
- 5Discuss the result with your healthcare team.
Quick reference
- A1C 5.0%: about 97 mg/dL, 5.4 mmol/L.
- A1C 6.0%: about 126 mg/dL, 7.0 mmol/L.
- A1C 7.0%: about 154 mg/dL, 8.6 mmol/L.
- A1C 8.0%: about 183 mg/dL, 10.2 mmol/L.
- A1C 9.0%: about 212 mg/dL, 11.7 mmol/L.
Understanding the ranges
The ranges used here are those of the American Diabetes Association and many other bodies: below 5.7 percent normal, 5.7 to 6.4 prediabetes, 6.5 and above in the diabetes range. Prediabetes can often be reversed or delayed with weight loss, activity and healthier eating. People with diabetes use their A1C, together with daily readings, to see how well their plan is working.
A1C cannot show the ups and downs behind the average. Two people with an A1C of 7 percent may have very different patterns: one steady, the other swinging between lows and highs. That is why people on insulin or with unstable readings also use continuous glucose monitors, which report time in range. Use this calculator to understand the average, and use daily readings or a monitor to see the pattern behind it.
Lowering your A1C
Healthy eating, regular physical activity, any medicines your doctor prescribes and good sleep and stress habits all help. Losing 5 to 7 percent of body weight can lower the risk of developing diabetes by more than half in people with prediabetes. Set targets with your care team rather than on your own, since the right target depends on your age and health.
Related tools
The Blood Sugar Converter switches between mg/dL and mmol/L, the Cholesterol Ratio Calculator and GFR Calculator look at other markers, and the BMI Calculator and Calorie Calculator help with weight and diet.
Features
- A1C %, mmol/mol, mg/dL and mmol/L
- ADAG study formula
- Range label
- Checks for unlikely values
- Instant conversion
- Private
Frequently asked questions
What is a normal A1C?
Below 5.7 percent is normal. 5.7 to 6.4 percent is the prediabetes range, and 6.5 percent or higher on two tests suggests diabetes. People with diabetes often have a personal target, commonly under 7 percent.
What is eAG?
Estimated average glucose: the average blood sugar level that matches a given A1C. An A1C of 7 percent corresponds to about 154 mg/dL, or 8.6 mmol/L.
How do I convert A1C to mmol/mol?
Subtract 2.15 from the percentage and multiply by 10.929. An A1C of 7 percent is about 53 mmol/mol, the figure used in the UK and many other countries.
Why does my meter average not match my A1C?
A1C reflects all hours of the day, including times you don't test, and is weighted toward recent weeks. Some conditions, such as anaemia, haemoglobin variants and kidney disease, can make A1C read higher or lower than your true average.
How often should A1C be tested?
People with diabetes are usually tested every three to six months. People at risk may be tested every one to three years. Your doctor will advise you.
Can this tell me whether I have diabetes?
No. Diagnosis needs lab tests interpreted by a doctor, often with a repeat test. The calculator only converts units and shows the ranges.