A1c Calculator
HbA1c % to mmol/mol and estimated average glucose, both ways.
About this tool
Enter any one of these: A1c in percent, A1c in mmol/mol, or average glucose in mg/dL or mmol/L. The tool shows all the others and where the result sits against the normal, prediabetes and diabetes ranges. Nothing is stored.
How A1c relates to average glucose
Glucose in the blood sticks to haemoglobin in red blood cells, which live for about three months. HbA1c (A1c) therefore reflects your average blood sugar over the past two to three months, weighted towards the most recent weeks. It's reported in two units: percent (the DCCT/NGSP scale, used in the US) and mmol/mol (the IFCC scale, used in the UK and much of Europe). The conversion is mmol/mol = (% โ 2.15) ร 10.929. The ADAG study linked A1c to average glucose with eAG (mg/dL) = 28.7 ร A1c โ 46.7, so an A1c of 7% is about 154 mg/dL (8.6 mmol/L), or 53 mmol/mol. Diagnostic bands (American Diabetes Association) are: below 5.7% (39 mmol/mol) normal, 5.7โ6.4% (39โ47) prediabetes, and 6.5% (48 mmol/mol) or above diabetes. UK guidance puts the prediabetes range at 42โ47 mmol/mol. Many adults with diabetes aim for around 7% (53 mmol/mol), but targets are personal. Honest limits: eAG is a population average, and individuals with the same A1c can have different averages. Anaemia, recent blood loss or transfusion, kidney disease, pregnancy and some haemoglobin variants can make A1c misleading. Not medical advice. The blood sugar converter and the net carbs calculator are related.
Frequently asked questions
What average blood sugar is an A1c of 7%?
About 154 mg/dL (8.6 mmol/L), using the ADAG formula eAG = 28.7 ร A1c โ 46.7.
How do I convert A1c percent to mmol/mol?
Subtract 2.15 and multiply by 10.929. 6.5% is 48 mmol/mol.
What A1c is prediabetes?
5.7โ6.4% (39โ47 mmol/mol) by US criteria. UK guidance uses 42โ47 mmol/mol.
Is my data stored?
No. Nothing is saved or sent. This isn't medical advice.