HbA1c converter

Convert HbA1c values

You can use the converter to change:

• mmol/mol to %

• % to mmol/mol

Both units describe the same measurement, just expressed in different ways.

HbA1c, also known as glycated haemoglobin, measures how much glucose is attached to your red blood cells. Because red blood cells live for around 2–3 months, the result reflects your average blood sugar level over that time rather than short-term day-to-day changes.

This makes HbA1c particularly useful for diagnosing diabetes, monitoring long-term glucose control, and assessing the risk of diabetes-related complications.

In the UK and most of Europe, HbA1c is reported in mmol/mol following international standardisation. Older UK results and many international sources still use percentage units.

Although the numbers can look very different, they represent the same underlying measurement. A value that appears high in one unit may simply be expressed differently in the other.

Using a converter can be helpful when reading older test results, comparing UK results with international guidelines, or reviewing information from overseas sources.

HbA1c results are usually interpreted alongside symptoms, medical history, and other blood tests. As a general guide:

• Results below 42 mmol/mol, which is equivalent to 6.0%, are often considered within the non-diabetic range.

• Results between 42 and 47 mmol/mol, equivalent to 6.0–6.4%, may indicate an increased risk of developing diabetes.

• Results of 48 mmol/mol (6.5%) or higher are commonly used as a threshold for diagnosing diabetes.

Target ranges may differ for people who already have diabetes, depending on age, overall health, and individual circumstances.

HbA1c is a useful long-term marker, but it does not tell the full story. Results can be affected by conditions that change red blood cell turnover or structure, such as anaemia, recent blood loss, pregnancy, kidney disease, or certain blood disorders.

If HbA1c results do not match symptoms or home blood glucose readings, further assessment may be needed.

HbA1c differs from finger-prick or fasting blood glucose tests, which show glucose levels at a single point in time. HbA1c provides a broader picture by averaging glucose exposure over several weeks.

For some people, particularly those with conditions affecting red blood cells, other tests may be more appropriate.

You should discuss HbA1c results with a healthcare professional if a result is higher than expected, changes significantly between tests, or does not seem to match how you feel.

Symptoms such as increased thirst, frequent urination, tiredness, or unexplained weight loss should always be checked.

A GP or diabetes specialist can explain what your result means for you and whether any action or follow-up is needed.

Is mmol/mol better than %?

Neither unit is better. They describe the same result in different ways. mmol/mol is the standard unit used in the UK.

Does converting HbA1c change what it means?

No. Conversion does not alter the underlying result, only how it is displayed.

How often is HbA1c measured?

For people with diabetes, HbA1c is often checked every 3–6 months, although this can vary.

Can I use this tool to diagnose diabetes?

No. Diagnosis should always be made by a healthcare professional using appropriate tests and clinical judgement.