HbA1c to average glucose (eAG) calculator
Short answer: An HbA1c of 6% means your blood sugar has averaged about 126 mg/dL (7.0 mmol/L) over the last two to three months, and 7% about 154 mg/dL (8.6 mmol/L). Each 1% of HbA1c is roughly 29 mg/dL (1.6 mmol/L) of average glucose. The conversion is the ADAG study formula: 28.7 × HbA1c − 46.7.
Free calculator
HbA1c to average glucose calculator (eAG)
Average glucose (mg/dL) = 28.7 × HbA1c (%) − 46.7
Sources: Nathan DM, Kuenen J, Borg R, et al. Translating the A1C assay into estimated average glucose values. Diabetes Care 2008;31(8):1473-1478.
In % (most labs) or mmol/mol (UK, EU, some Gulf labs)
Your result
Enter the numbers from your lab report to see your result.
HbA1c follows your red cells, so anaemia, a recent blood loss or transfusion, pregnancy, kidney disease and some haemoglobin variants can make it read higher or lower than your real average.
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A pointer, not a diagnosis. Talk to a doctor about your result, and sooner if you feel unwell.
How to read the result
- Normal (HbA1c below 5.7%)< 5.7%Your HbA1c is in the normal range: your blood sugar has averaged at a healthy level over the last two to three months.
- Prediabetes (5.7 to 6.4%)5.7 – 6.5%This is the prediabetes range: blood sugar has been running higher than it should, but not at diabetes level. It is common and often turns around with more movement, less sugar and refined carbs, and better sleep. A doctor can confirm it with a second test.
- Diabetes range (6.5% or above)≥ 6.5%An HbA1c of 6.5% or above is in the diabetes range. One result is not a diagnosis: doctors confirm it with a second test. Please talk to a doctor about it soon.
Your lab’s range
Lab reports print the same HbA1c cut-offs: below 5.7% (39 mmol/mol) normal, 5.7–6.4% (39–47 mmol/mol) prediabetes, 6.5% (48 mmol/mol) or above diabetes. Some apps and clinics show a stricter "optimal" level below 5.4%; the lab range above is what doctors diagnose from.
How it is worked out
Average glucose (mg/dL) = 28.7 × HbA1c (%) − 46.7
HbA1c follows your red cells, so anaemia, a recent blood loss or transfusion, pregnancy, kidney disease and some haemoglobin variants can make it read higher or lower than your real average.
Sources
- Nathan DM, Kuenen J, Borg R, et al. Translating the A1C assay into estimated average glucose values. Diabetes Care 2008;31(8):1473-1478.
- American Diabetes Association Professional Practice Committee. 2. Diagnosis and classification of diabetes: Standards of Care in Diabetes—2025. Diabetes Care 2025;48(Suppl 1):S27-S49.
The markers it uses
Questions
- How do I convert HbA1c to average blood sugar?
- Multiply your HbA1c (%) by 28.7 and subtract 46.7 to get your estimated average glucose in mg/dL. In mmol/L it is about 1.59 × HbA1c − 2.59. So 6% is about 126 mg/dL (7.0 mmol/L), 7% about 154 mg/dL (8.6 mmol/L) and 8% about 183 mg/dL (10.2 mmol/L).
- What is a normal HbA1c and average glucose?
- An HbA1c below 5.7% is normal; that is an average glucose below about 117 mg/dL (6.5 mmol/L). 5.7 to 6.4% is prediabetes, and 6.5% or above is the diabetes range. Doctors confirm a diagnosis with a second test.
- What is eAG?
- Estimated average glucose: the average blood sugar that goes with an HbA1c, in the same units as a glucose meter. It comes from the ADAG study (Nathan and colleagues, Diabetes Care 2008), which compared HbA1c with thousands of glucose readings in the same people.
- Is eAG the same as GMI from a CGM?
- No. GMI goes the other way, from a continuous glucose monitor’s average to an estimated HbA1c, with a different formula (3.31 + 0.02392 × average mg/dL). Both are estimates, and a lab HbA1c can differ from either by half a percent or more. You can work out your GMI from a sensor export at healthosx.com/glucose.
- What can make HbA1c misleading?
- Anything that changes how long red cells live: anaemia, iron deficiency, a recent blood loss or transfusion, pregnancy, kidney disease and some haemoglobin variants such as sickle cell trait. Then a glucose average from a meter or sensor says more.
More calculators for the same system
A pointer, not a diagnosis. Talk to a doctor about your result, and sooner if you feel unwell. Reference ranges are general-population guidance compiled from common clinical laboratories, not a diagnosis. Lab-to-lab ranges differ. Always read your results with your doctor.