HbA1c to Average Glucose Calculator (mg/dL, mmol/L)

How to use it

Enter the number from your report in HbA1c result.
Choose the unit of the result in Unit of the result: percent or mmol/mol.
Read the Estimated average glucose in mg/dL and mmol/L, and the same HbA1c in the other unit.

How the conversion is calculated

The American Diabetes Association (ADA) converts HbA1c to an estimated average glucose (eAG) with a straight-line formula. In mg/dL, eAG = 28.7 × HbA1c − 46.7. For mmol/L, the mg/dL figure is divided by 18.0156, the number of mg/dL in one mmol/L of glucose.

The two HbA1c units are linked by the IFCC–NGSP master equation. The percent value (NGSP) is 0.09148 times the mmol/mol value (IFCC) plus 2.152, and the mmol/mol value is 10.93 times the percent value minus 23.50.

This is not medical advice. HbA1c is one test, and your doctor or diabetes team reads it with your other results and your history. Do not change medicines or diet because of this estimate; talk to them first.

eAG (mg/dL)        = 28.7 × HbA1c (%) − 46.7
eAG (mmol/L)       = eAG (mg/dL) ÷ 18.0156
HbA1c (%) (NGSP)   = 0.09148 × HbA1c (mmol/mol) + 2.152
HbA1c (mmol/mol)  = 10.93 × HbA1c (%) − 23.50

What the figure is and is not

A conversion of an HbA1c result into an average glucose. It is not a glucose reading, and it cannot replace your meter or sensor readings.
A straight-line formula. It gives one average figure, not the range your glucose moves through in a day.
Not a diagnosis. If the figure does not match your own readings, ask your doctor to explain the result.

Worked example: an HbA1c of 7 %

28.7 × 7 − 46.7 = 154.2, shown as 154 mg/dL. Divided by 18.0156, that is 8.6 mmol/L.

The same result in mmol/mol is 10.93 × 7 − 23.5 = 53.0, shown as 53 mmol/mol.

Measure	Result
HbA1c in percent (NGSP)	7.0
HbA1c in mmol/mol (IFCC)	53
Average glucose (mg/dL)	154
Average glucose (mmol/L)	8.6

Frequently asked questions

Why does the calculator give two HbA1c units?

Laboratories report HbA1c either in percent (NGSP) or in mmol/mol (IFCC), so the same test can be printed either way. The page converts between them and gives the average glucose in both glucose units.

Where do the formulas come from?

The glucose formula is the ADA's conversion, shown on its eAG/A1C calculator. The link between the two HbA1c units is the IFCC–NGSP master equation published by NGSP.

Why does my average glucose not match my meter?

The formula gives an average from the HbA1c result. A meter shows readings at particular times, so the two can differ. Your doctor can explain your results.

Can I use this to change my treatment?

No. This page does not give targets or treatment. Your doctor or diabetes team sets your targets and decides on any change to your medicines.

Is anything I enter sent to a server?

No. The calculation runs in your browser and nothing you enter is sent to us.

Sources

Figures and text last checked on Thursday, November 12, 2026.

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