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HbA1c Unit Converter
Hemoglobin A1c (HbA1c) reflects the average blood glucose concentration over the preceding 2 to 3 months. It is the gold standard for monitoring long-term glycemic control in diabetes mellitus.
Historically, results have been reported as a percentage (NGSP, used in the US). However, the international community has moved towards the IFCC standard (mmol/mol). This calculator converts between these two units and provides the estimated Average Glucose (eAG).
Primary Units
InputStandard US Unit
mmol/mol (International)
Estimated Average Glucose
eAG correlates the HbA1c result with daily glucose monitoring values.
Clinical Context
Diagnostic Criteria (ADA):
• Normal: HbA1c < 5.7% (< 39 mmol/mol).
• Prediabetes: 5.7% – 6.4% (39 – 47 mmol/mol).
• Diabetes: ≥ 6.5% (≥ 48 mmol/mol).
Formulas (ADAG Study):
• IFCC (mmol/mol) = (10.93 × NGSP%) − 23.5
• eAG (mg/dL) = (28.7 × NGSP%) − 46.7
• eAG (mmol/L) = (1.59 × NGSP%) − 2.59
Clinical References
How to Use This Converter
Follow these steps to convert HbA1c values.
Enter a Value
Input your lab result into either the NGSP (%) field or the IFCC (mmol/mol) field.
Automatic Calculation
The tool automatically converts to the other unit and calculates the Estimated Average Glucose (eAG).
Reset
Use the Clear button to reset all fields.
Frequently Asked Questions
eAG reports A1c in the same units (mg/dL or mmol/L) as daily glucose meters, making it easier for patients to understand the relationship between their daily monitoring and long-term control.
No, they are different ways of reporting the same molecule. NGSP measures the percentage of hemoglobin that is glycated, while IFCC measures the molar concentration.