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A1c Calculator – Hemoglobin A1c to Average Blood Sugar

Table of contents

What is A1c – glycated hemoglobin?When should I get my hemoglobin A1c test?How to calculate A1c to average blood sugar?Normal A1c range – A1c levels chartRisks of chronic high blood glucose level – prediabetes state, diabetes, complicationsHow to lower A1c?FAQs

If you have ever wondered what those enigmatic numbers on your laboratory blood test result are – this A1c calculator is here for you. It transforms the result of your hemoglobin A1c test (HbA1c) into average blood sugar level – and also the other way around! In the following article, you'll get to grips with what A1c is and what are its normal ranges. Read on to find out how to calculate A1c manually, the dangers of high glycated hemoglobin A1c levels, and how to lower A1c when needed.

See the blood sugar converter, too!

We try our best to make our Omni Calculators as precise and reliable as possible. However, this tool can never replace a professional doctor's assessment.

What is A1c – glycated hemoglobin?

Hemoglobin may sound familiar to you – something about oxygen transportation, right? Hemoglobin A1c (HbA1c) is quite close to what you remember from your biology classes. Although it sounds like the name of a robot, it is actually a special form of hemoglobin where the molecule has a particle of sugar (glucose) attached. Everybody has some glycated hemoglobin in their bloodstream, and the amount of it increases as your blood sugar levels increase. Laboratory A1c test measures the percentage of hemoglobin that has glucose bound to it. But why is the result not the same as a simple blood sugar level test?

You might already know that our red blood cells live, on average, 120 days – or four months. Hemoglobin is found inside Red Blood Cells (RBC), so we can assume that it lives for as long as them. To be exact, and to take into consideration the varying lifespans of red blood cells, scientists assume that A1c hemoglobin stays in the body for about 90 days – and, therefore, reflects the last three months of blood sugar levels. This is why your doctor will get more information about your risk of metabolic disorders from an A1c test than from a simple blood sugar level test.

When should I get my hemoglobin A1c test?

You should test your A1c levels as a preventive test if you are over 45 or under 45 and overweight. You should also consider it if you have one of the diabetes risk factors, such as:

  • History of familial diabetes (parents or siblings);
  • Low physical activity (less than three times a week);
  • High blood pressure;
  • High level of blood cholesterol; and
  • History of gestational diabetes or having given birth to a baby weighing over 9 pounds.

Check out your individual diabetes risk with our comprehensive diabetes risk calculator.

How to calculate A1c to average blood sugar?

  1. There's nothing more simple than using our A1c calculator. Just input the level of hemoglobin A1c from your laboratory test to get your result immediately. You can freely switch between units in both the hemoglobin and average blood sugar fields.

  2. For those curious about the actual calculations, here is the A1c (%) to average blood sugar (mg/dL) formula:

    Average Blood Sugar (mg/dL) = HbA1c (%) × 28.7 - 46.7

  3. If you want to convert hemoglobin A1c level from a percent (%) to millimoles per mole (mmol/mol), use the following equation:

    HbA1c (mmol/mol) = HbA1c (%) × 10.93 - 23.5

  4. To do the reverse calculation (from mmol/mol to %), use this formula:

    HbA1c (%) = HbA1c (mmol/mol) × 0.09148 + 2.152

Normal A1c range – A1c levels chart

If you have or are likely to have a metabolic disorder, your doctor will insist that you do this particular laboratory test, as it has information about you from the last three months. On the other hand, one finger-prick blood sugar level test shows the state of the body at that particular moment. A simple blood test is still a valuable and significant measure – each of these tests has its purpose.

CDC reports that the safe and healthy limits of HbA1c are as follows:


Under 5.7%




Over 6.4%

Do not ignore a result of over 5.7%. Below, you can find out how to lower A1c.

Risks of chronic high blood glucose level – prediabetes state, diabetes, complications

You already know how to calculate A1c levels, but what should you do with the result? If your level is less than 5.7% – congratulations – this is a normal A1c level, and you have nothing to worry about. Maintain your healthy habits and keep your blood sugar level low.

If you drifted into the prediabetes group (5.7-6.4%) – that's a red flag. You're at a high risk of diabetes, but there is still hope. Check out the How to lower A1c? section for some hints. Do not neglect this result, as chronic high blood sugar levels can lead to severe consequences, including:

  • Increased risk of cardiovascular diseases – myocardial infarction (heart attack) or brain stroke;
  • Risk of chronic kidney disease or even kidney failure;
  • Increased risk of nerve damage (including brain damage) and paresthesia;
  • High risk of retinopathy and loss of sight;
  • Frequent infections, including skin infections and mycoses;
  • Problems getting pregnant;
  • Diabetic foot, potentially leading to amputation!

If your A1c level is equal to or higher than 6.5%, you may be diagnosed as diabetic. If this is your result, book an appointment with your doctor immediately!

How to lower A1c?

If your A1c test shows that your levels are too high, your doctor will tell you to lower them. Here are some useful tips on how to do that:

  1. Discuss medication with your diabetologist. Make sure that you're taking them as the doctor ordered. Mention other drugs that you're taking for other conditions – they may influence one another.

  2. Check your blood sugar levels more often and make sure you're using the right interventions to manage it (e.g., the proper dose of insulin or a well-balanced meal). Seek professional help if you feel that this is your weakness.

  3. Move more. You don't have to become an Olympic athlete, but, for example, try to incorporate a few short walks into your normal day. Every step counts!

  4. Try to achieve and maintain a normal body weight. Use the BMI calculator to check your current weight and see where you should head to.

  5. BMI is the basic indicator, but pay attention also to your waist-hip ratio (use our waist-to-hip ratio calculator, for example). An excess of visceral fat (the fat tissue that surrounds your internal organs) is linked to a higher risk of diabetes and heart disease.

  6. Stick to a healthy, balanced diet. Do not exceed your daily calorie limit, or try to eat even a little less if you're overweight. Say goodbye to sweets and processed foods.

If you take those tips seriously, you will surely notice some positive changes in your hemoglobin A1c levels.


What is a1c?

Hemoglobin a1c (HbA1c) is known as glycated hemoglobin or hemoglobin with an attached sugar (glucose) molecule in the Red Blood Cell (RBC). The level of hemoglobin a1c increases or decreases depending on the blood sugar level in the body.

What does my a1c level show?

Hemoglobin a1c (HbA1c) levels indicate the blood sugar level over the last three months (90 days). The time frame is based on the red blood cells' lifespan of 4 months (120 days).

What is a normal level of a1c?

Under 5.7% of hemoglobin a1c is considered normal. The higher the level of hemoglobin a1c, the higher the risk of prediabetes and diabetes.


Hemoglobin a1c level


Under 5.7%


5.7% - 6.4%


Over 6.4%

What is the normal HbA1c level for men and women?

Men have significantly higher levels of HbA1c compared to women. It is also true that HbA1c levels slowly rise as we age.

There is no exact percentage of HbA1c levels for men and women.

What is a dangerous level of a1c?

More than 6.4% of hemoglobin a1c is considered dangerous. Even so, if your HbA1c level is between 5.7% and 6.4%, that is already a sign of prediabetes. It is highly recommended that you consult a physician and get your blood sugar levels under control.

How do I lower my a1c level?

Here are a few things you can do to lower your HbA1c level:

  • Consult your doctor about diet and medications;
  • Check your a1c level more often;
  • Eat a healthy, balanced diet;
  • Be physically active; and
  • Maintain a normal body weight and BMI.

What factors can affect a1c level?

Factors affecting hemoglobin a1c levels include:

  • Age, gender, and ethnicity;
  • Comorbidity from other illnesses;
  • The use of some medications;
  • Blood loss or gain; and
  • Pregnancy.
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