Blood sugar
HbA1c → average glucose calculator
Convert your HbA1c percentage into an estimated average glucose (eAG) in mg/dL and mmol/L, and see how the value maps onto the normal, prediabetes, and diabetes ranges.
Enter your values above to see your result and what it means.
What is estimated average glucose (eAG)?
Estimated average glucose, or eAG, translates your HbA1c percentage into the same units as a day-to-day blood sugar meter (mg/dL or mmol/L). It is derived from a standard formula relating A1c to roughly three months of average blood glucose, so a single A1c becomes a number that feels more familiar. This makes it easier to connect a lab percentage to the readings you see at home.
How to convert A1c to average glucose
The widely used conversion estimates average glucose in mg/dL as 28.7 times your A1c minus 46.7, and this tool applies it and also shows the mmol/L value. Because it is an average, eAG smooths out the daily highs and lows rather than replacing finger-stick readings. The result is an estimate, so treat small differences between eAG and your meter as normal.
What is a normal A1c level?
Laboratories and the ADA commonly describe A1c bands for normal, prediabetes, and diabetes ranges, but the exact cut-offs and how they apply to you depend on your clinical situation and the lab’s reference range. This calculator shows which ADA band your entry falls into for context, not as a diagnosis. Always read it next to the reference range printed on your own report.
Is 5.7 A1c prediabetes? Understanding the bands
A1c values are often grouped so that a range below the prediabetes cut-off is considered normal, an intermediate range is labelled prediabetes, and higher values fall in the diabetes range — 5.7 is the value many guidelines use as the lower edge of the prediabetes band. A band is a screening signal, not a verdict; results can be affected by certain anaemias and other conditions. Confirm any interpretation with a clinician.
Why A1c and a single glucose reading can disagree
A finger-stick or fasting glucose captures one moment, while A1c (and the eAG it converts to) reflects an average over weeks. So a normal morning reading can still sit alongside a higher A1c, and vice versa. Seeing both the percentage and the estimated average together helps explain why the two tests answer slightly different questions.
Frequently asked questions
Is an HbA1c of 6.5% a diabetes diagnosis?
It meets the diagnostic threshold, but a diagnosis is not made on a single test. It is normally confirmed with a repeat HbA1c or another glucose test by a clinician, unless you also have clear symptoms and a very high glucose.
How does HbA1c relate to my glucose meter readings?
HbA1c is a 2–3 month average, while a meter shows a single moment. The estimated average glucose (eAG) converts your HbA1c into the same units your meter uses so the two are easier to compare — but your meter will still show higher and lower values around that average.
Can my HbA1c be falsely high or low?
Yes. Anaemia, recent blood loss or transfusion, pregnancy, kidney disease, and inherited haemoglobin variants can all shift HbA1c away from your true average glucose. If your result does not fit how you feel or your meter readings, mention these possibilities to your clinician.
What units should I enter?
Enter the percentage (the DCCT/NGSP value, e.g. 5.6%). If your result is reported in mmol/mol (the IFCC unit), this calculator does not take that directly — ask for the % value or convert it first.