A1c Calculator And A1c Conversion Chart
Written By Kobi Nathan, Pharm.D., M.Ed., CDP, BCGP, AGSF
Sleep Disorders
April 5, 2023

The A1C test is extremely important to managing diabetes, providing a peak into your overall blood sugar control over the past three months.

In this article, we’ll dive into the details of the A1C test, its calculation, and its significance in diabetes management.

But there’s a handy chart AND built-in conversion calculator you can use if you don’t want to bother with calculating your A1c number out!

Here are the calculator and the conversion table if you want to estimate your own numbers quickly:

Table of Contents

A1c Calculator

 

eAG/A1C Conversion Calculator


A1C to eAG eAG to A1C
mg/dl mmol/l

Result:

0.00

 

A1c Conversion Chart

 

Quick Reference Table For A1c and Estimated Average Glucose (eAG) Levels

A1ceAG
%mg/dLmmol/L
61267.0
6.51407.8
71548.6
7.51699.4
818310.1
8.519710.9
921211.8
9.522612.6
1024013.4

If you want to know more about the A1c test, here’s more information:

Introduction to A1C Test

The A1C test, or the glycated hemoglobin test, HbA1c, or simply A1C, measures your average blood glucose level over the past 2-3 months. It does this by calculating the percentage of glycated hemoglobin (a form of hemoglobin bonded with glucose) in the bloodstream.

Glycated hemoglobin forms when glucose molecules attach to hemoglobin molecules. The more glucose in the blood, the higher the percentage of glycated hemoglobin, or A1c value.

So, if your A1c is higher than expected, your blood test tells your doctor that your diabetes care has not been well-controlled for the past three months.

The A1C Formula

The A1C number is typically expressed as a percentage. The formula for calculating the A1C number is as follows:

To calculate the A1C number, laboratories measure the total glycated hemoglobin and total hemoglobin in a blood sample. By dividing the total glycated hemoglobin by the total hemoglobin and multiplying by 100, the A1C percentage is obtained.

This is a simple and routine blood test that your doctor will order, together with other labs required to make sure your diabetes is under control.

 

A1C to Estimated Average Glucose (eAG)

For a more practical understanding of blood sugar levels, healthcare professionals often convert the A1C percentage to Estimated Average Glucose (eAG). The eAG is measured in the same units (mg/dL or mmol/L) used by glucose meters, which makes it easier for patients to relate to their daily glucose monitoring.

Furthermore, this equation works well for people with both Type 1 and Type 2 Diabetes.

The eAG Formula

The formula for converting A1C to eAG in mg/dL is as follows:

(28.7 × A1C) – 46.7 = eAG (mg/dL)

Or, for measurements in mmol/L:

You would divide the calculated eAG in mg/dL above by 18.015 = eAG in mmol/L.

Let’s apply this equation in an example.

Average blood glucose calculation

Let’s say you have three daily glucose readings, one from before breakfast and two random ones before and after meals: (140, 119, 158). To get the average, you would add all three numbers and divide by 3:

(140 + 119 + 158) / 3 = 139 mg/dL (eAG).

A1c calculation

You would plug the eAG you calculated above into the equation as follows to determine your A1c:

(28.7 x A1c) – 46.7 = 139

(28.7 x A1c) = 139 + 46.7

A1c = (139 + 46.7) / 28.7 = 6.47.

By applying these formulas, you can convert the A1C percentage to eAG values, which provide a clearer representation of your average blood sugar level.

Or, if you have daily blood glucose levels from your sugar monitor, you can average them out and use that value in the equation to find out what your A1c is.

Interpreting A1C Results

The American Diabetes Association (ADA) has established guidelines for interpreting Hemoglobin A1C test results:

  • Normal: A1C below 5.7%.
  • Prediabetes: A1C between 5.7% and 6.4%.
  • Diabetes: A1C of 6.5% or higher.

It’s essential to note that the above values only apply to younger, healthier, community-dwelling adults. The blood glucose goals are very different for older, frail adults.

To understand why, please read my article on hyperglycemia vs hypoglycemia here, where I go into great detail about glucose management in older adults.

Individual targets may vary based on factors such as age, duration of diabetes, and the presence of other health conditions. Always consult your healthcare provider for personalized guidance on target A1C levels and management strategies.

Factors Affecting A1C Accuracy

While the A1C test is a valuable tool for monitoring diabetes, several factors can impact its accuracy:

Hemoglobin variants: Genetic differences in hemoglobin can affect A1C measurements. For example, people with sickle cell anemia or thalassemia may have falsely low or high A1C results, respectively.

Changes in red blood cell lifespan: The average lifespan of red blood cells is approximately 120 days. However, conditions such as anemia, kidney disease, or recent blood transfusions can alter this lifespan, potentially skewing A1C results.

Pregnancy: Pregnant women may experience changes in their red blood cells that could result in inaccurate A1C readings.

Lab variations: Different laboratories may use different techniques to measure A1C, leading to slight variations in the results. Ensuring that the same laboratory is used for consistent A1C testing is essential.

Importance of A1C in Diabetes Management

The A1C test is crucial in diabetes management as it provides a long-term picture of your blood sugar control. Regular A1C testing helps healthcare providers:

  • Assess the effectiveness of current treatment plans.
  • Make necessary adjustments to medications, lifestyle, or diet.
  • Monitor progress toward blood sugar control goals.

 

Not taking charge of your blood glucose control could lead to long-term health problems such as Cerebral Small Vessel Disease (CSVD) or Vascular Dementia, among others. I highly recommend you read my detailed articles on these topics linked above.

However, it’s important to remember that A1C is only one aspect of diabetes management.

Regular self-monitoring of blood glucose, maintaining a healthy diet, engaging in regular physical activity, and following your healthcare provider’s recommendations are all essential to effective diabetes management.

Conclusion

Understanding how the A1C number is calculated and its significance in diabetes management is crucial for individuals with this condition.

The A1C test gives you and your medical provider a good sense of how you have managed your blood sugar over the last 2 to 3 months.

Knowing this number will help you identify possible barriers to your self-care and plan effective management strategies for your diabetes.

However, some factors can influence the accuracy of your A1C results. Examples include changes in red blood cell lifespan, pregnancy, or lab variations.

Always consult your healthcare provider to ensure you fully understand your target A1C levels.

The A1C test is just one small part of your overall diabetes management plan.

By combining regular A1C testing with self-monitoring of blood glucose, maintaining a healthy lifestyle, and following your doctor’s recommendations, you can comfortably manage your diabetes and reduce the risk of serious complications.

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