HB A1C (Haemoglobin A1C ) Calculator

The Hb A1c is blood test that provides a method of monitoring a person with diabetes blood sugar levels over the previous 3 months.

The Hb A1c can be used to work out the estimated average glucose (eAG) level using a complex mathematical model.

Enter your Hb A1c to understand what you average blood sugar value has been over the previous 3 months.

How to use the tool:

Enter your Hb A1c value from your last blood test to understand what you average blood sugar value has been over the previous 3 months.

Let’s assess your

Risk of Developing Complications


Choose either percentage or mmol/mol depending on what is written on your blood laboratory result.


Range 5 - 16%

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What is Hb A1c test?

The HbA1c test, or the glycated haemoglobin A1c test, is a blood test that can be taken at any time as you don’t need to fast before taking the test. It indicates what your average blood glucose levels are over the past 3 months, by measuring the percentage of blood glucose that has attached to haemoglobin. Haemoglobin is the oxygen carrying protein found in red blood cells.

It is normal for all people to have some glucose attached to haemoglobin. In people with diabetes, the higher the blood glucose levels are, the more glucose you have attached to haemoglobin. A HbA1c level of 6.5% or higher, on two separate tests, can indicate that you have diabetes. Whereas a HbA1c level between 5.7 and 6.4% can indicate prediabetes. Levels below 5.7% are considered normal. In other words, higher A1c percentages indicate an increased risk of diabetes.

The HbA1c test should not be used alone to diagnose diabetes. It should be used in combination with other blood glucose tests.

What does a high Hb A1c reading mean?

There is a strong relationship between high Hb A1c readings and the risk of developing diabetes-related complications.

Why is Hb A1c tested every 3 months?

You Hb A1c is tested every 3 months because our bodies make new red blood cells 3 months.

Your Hb A1c reading from last week won’t be the same as your Hb A1c reading from last year.

estimated Average Glucose

The estimated Average Glucose (eAG) is a way to show patients what their Hb A1c results (shown as a percentage) are using the same units (mg/L or mmol/L) that they're more familiar with when monitoring their blood glucose levels.

Hb A1c and corresponding estimated average glucose level table

Hb A1c and corresponding estimated average glucose values
Hb A1c % Hb A1c mmol/mol eAG mg/dl eAG mmol/l

What is a normal Hb A1c reading?

A normal haemoglobin (Hb) A1c level is below 5.7%. Therefore, a healthy Hb A1c value is below 5.7%.