A1C Calculator

Q: What is a good A1C number?

A good A1C number is below 5.7% . 2 This means your blood sugar has been in a normal, healthy range over the past 2 to 3 months. If you already have diabetes, the American Diabetes Association's goal for many nonpregnant adults is below 7% , but your own goal may be different depending on your health. 4

Q: What is the difference between A1C and eAG?

A1C is shown as a percentage and reflects your average blood sugar over 2 to 3 months. eAG (estimated average glucose) is that same information shown in mg/dL or mmol/L , which matches the units on your home glucose meter. They tell you the same thing, just in different formats.

Q: What is IFCC and how is it different from NGSP?

NGSP reports A1C as a percentage (like 6.5%). IFCC reports A1C in mmol/mol (like 48 mmol/mol). They measure the same thing but use different units, linked by the master equation NGSP = 0.915 × IFCC + 2.15%. 3 The NGSP system is common in the United States, while the IFCC system is used in many other countries. This calculator shows both.

Q: What does an A1C of 7% mean in everyday blood sugar numbers?

An A1C of 7% equals an estimated average glucose of about 154 mg/dL (or 8.6 mmol/L). This means that over the past 2 to 3 months, your blood sugar averaged around that level throughout the day and night. 1

Q: What is the difference between mg/dL and mmol/L?

These are two different units for measuring blood sugar. mg/dL (milligrams per deciliter) is used mainly in the United States. mmol/L (millimoles per liter) is used in most other countries. To convert, divide mg/dL by 18. For example, 180 mg/dL = 10.0 mmol/L.

Q: Is A1C the same as fasting blood sugar?

No. Fasting blood sugar is a snapshot of your blood sugar level at one single moment after not eating for 8 to 12 hours. A1C shows your average blood sugar over the past 2 to 3 months. Both tests are used to diagnose diabetes, but they measure different things.

Q: What A1C level is considered prediabetes?

An A1C between 5.7% and 6.4% is considered prediabetes. This means your blood sugar is higher than normal but not high enough to be called diabetes. 2 Prediabetes is a warning sign, and making lifestyle changes now can help prevent type 2 diabetes.

Introduction

The A1C calculator helps you understand your average blood sugar levels over the past 2 to 3 months. A1C is a simple blood test that measures how much sugar is attached to your red blood cells. Doctors use this number to check if your blood sugar is in a healthy range or if you might have diabetes or prediabetes. A normal A1C level is below 5.7%, while 5.7% to 6.4% means prediabetes, and 6.5% or higher means diabetes.

With this tool, you can convert your A1C percentage to an estimated average glucose (eAG) level, or go the other way and convert your average blood sugar to an A1C number.² This makes it easier to see what your daily blood sugar readings mean in terms of your overall health. This calculator gives you a quick and clear picture of where your blood sugar stands.

How to Use Our A1C Calculator

Enter your average blood sugar level below, and this calculator will estimate your A1C percentage. A1C shows your average blood sugar over the past 2 to 3 months.

Average Blood Sugar Level: Type in your average blood sugar number in mg/dL. You can get this number from a blood glucose meter or a continuous glucose monitor (CGM). This is the main number the calculator uses to figure out your A1C result.

What Is A1C?

A1C (also called hemoglobin A1C or HbA1c) is a blood test that shows your average blood sugar level over the past 2 to 3 months. It works by measuring how much sugar is attached to the hemoglobin in your red blood cells. Hemoglobin is a protein inside red blood cells that carries oxygen through your body. When sugar builds up in your blood, it sticks to hemoglobin. The more sugar in your blood, the higher your A1C number will be.

Why Does A1C Matter?

Doctors use the A1C test to diagnose type 2 diabetes and prediabetes. It is also used to monitor how well people with diabetes are managing their blood sugar over time. Unlike a regular blood sugar test that only shows your level at one moment, the A1C gives a bigger picture of your overall blood sugar control. Understanding your A1C alongside other health markers, such as your body fat percentage and waist-to-hip ratio, can help paint a more complete picture of your metabolic health.

Understanding A1C Levels

Normal: Below 5.7%
Prediabetes: 5.7% to 6.4%
Diabetes: 6.5% or higher

Those are the American Diabetes Association's 2024 criteria: prediabetes at an A1C of 5.7 to 6.4% (39 to 47 mmol/mol) and diabetes at 6.5% (48 mmol/mol) or higher.² For most people who already have diabetes, the American Diabetes Association recommends an A1C goal of below 7%.⁴ However, your doctor may set a different target based on your age, health, and other factors. Kidney function can also be affected by prolonged high blood sugar, so tracking your GFR (glomerular filtration rate) is another important part of diabetes management.

A1C and Estimated Average Glucose (eAG)

Your A1C percentage can be converted into an estimated average glucose (eAG) number, shown in mg/dL. The conversion comes from a 2008 study of 507 people whose average glucose over three months tracked A1C as 28.7 × A1C − 46.7.¹ This makes it easier to understand because it uses the same units as your daily blood sugar readings from a glucose meter. For example, an A1C of 7% equals an eAG of about 154 mg/dL.¹

How to Lower Your A1C

If your A1C is too high, there are steps you can take to bring it down:

Eat a balanced diet with fewer processed sugars and refined carbs
Exercise regularly: aim for at least 30 minutes most days
Take medications as prescribed by your doctor
Check your blood sugar regularly to track patterns
Stay at a healthy weight
Stay hydrated

Lowering your A1C reduces your risk of diabetes-related complications like heart disease, kidney damage, and nerve problems. Talk to your doctor about how often you should get your A1C tested and what your personal goal should be.

Formulas used

A1C to eAG (mg/dL) ¹

\text{eAG (mg/dL)} = (28.7 \times \text{A1C}) - 46.7

eAG to A1C ¹

\text{A1C (\%)} = \frac{\text{eAG (mg/dL)} + 46.7}{28.7}

mg/dL to mmol/L Conversion

\text{eAG (mmol/L)} = \frac{\text{eAG (mg/dL)}}{18.0}

NGSP to IFCC Conversion

\text{IFCC (mmol/mol)} = (\text{NGSP} - 2.15) \times 10.929

Frequently asked questions

What is a good A1C number?

A good A1C number is below 5.7%.² This means your blood sugar has been in a normal, healthy range over the past 2 to 3 months. If you already have diabetes, the American Diabetes Association's goal for many nonpregnant adults is below 7%, but your own goal may be different depending on your health.⁴

What is the difference between A1C and eAG?

A1C is shown as a percentage and reflects your average blood sugar over 2 to 3 months. eAG (estimated average glucose) is that same information shown in mg/dL or mmol/L, which matches the units on your home glucose meter. They tell you the same thing, just in different formats.

What is IFCC and how is it different from NGSP?

NGSP reports A1C as a percentage (like 6.5%). IFCC reports A1C in mmol/mol (like 48 mmol/mol). They measure the same thing but use different units, linked by the master equation NGSP = 0.915 × IFCC + 2.15%.³ The NGSP system is common in the United States, while the IFCC system is used in many other countries. This calculator shows both.

How often should I get my A1C tested?

If results are normal, the American Diabetes Association says testing should be repeated at a minimum of 3-year intervals, and people with prediabetes should be tested yearly.² If you have diabetes, you should get tested every 3 to 6 months to see how well your treatment plan is working.

Can my A1C be wrong or inaccurate?

Yes. Certain conditions can make your A1C result higher or lower than expected. These include anemia, sickle cell disease, kidney disease, recent blood transfusions, and pregnancy. Some vitamin supplements like iron or vitamin B12 can also affect results. If your A1C doesn't match your daily glucose readings, talk to your doctor.

What does an A1C of 7% mean in everyday blood sugar numbers?

An A1C of 7% equals an estimated average glucose of about 154 mg/dL (or 8.6 mmol/L). This means that over the past 2 to 3 months, your blood sugar averaged around that level throughout the day and night.¹

What is the difference between mg/dL and mmol/L?

These are two different units for measuring blood sugar. mg/dL (milligrams per deciliter) is used mainly in the United States. mmol/L (millimoles per liter) is used in most other countries. To convert, divide mg/dL by 18. For example, 180 mg/dL = 10.0 mmol/L.

Is A1C the same as fasting blood sugar?

No. Fasting blood sugar is a snapshot of your blood sugar level at one single moment after not eating for 8 to 12 hours. A1C shows your average blood sugar over the past 2 to 3 months. Both tests are used to diagnose diabetes, but they measure different things.

What A1C level is considered prediabetes?

An A1C between 5.7% and 6.4% is considered prediabetes. This means your blood sugar is higher than normal but not high enough to be called diabetes.² Prediabetes is a warning sign, and making lifestyle changes now can help prevent type 2 diabetes.

How quickly can I lower my A1C?

Since A1C measures a 2- to 3-month average, it usually takes about 3 months of consistent changes to see a noticeable drop. Some people see results in as little as 2 months. Diet changes, exercise, and medication (if prescribed) all help bring your A1C down over time.

Sources

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