A1C Calculator
Free A1C calculator — convert between HbA1c percentage and estimated average glucose (eAG) in mg/dL and mmol/L.
Everyday Uses
Track control
Translate an A1C result into an average glucose you recognise.
Both directions
Convert glucose readings back into an estimated A1C.
mg/dL & mmol/L
Switch between US and international glucose units.
Context
See where a value sits versus standard reference ranges.
Frequently Asked Questions
What is A1C and what does it measure?
A1C (HbA1c) is a blood test that reflects your average blood glucose over the past two to three months, reported as a percentage. It measures how much glucose has attached to haemoglobin in your red blood cells. Standard ranges are: normal below 5.7%, prediabetes 5.7–6.4%, and diabetes 6.5% or higher.
How do you convert A1C to average glucose?
The estimated average glucose (eAG) is: mg/dL = 28.7 × A1C − 46.7. Divide mg/dL by 18.0182 for mmol/L. So an A1C of 6.5% equals about 140 mg/dL or 7.8 mmol/L. This calculator converts in both directions.
Is this A1C calculator medical advice?
No. It converts between A1C and average glucose using the standard ADAG formula for general information only. It is not a diagnosis or a substitute for laboratory testing. Always discuss your A1C and glucose results with a healthcare professional.