How To Convert A1C To Average Blood Sugar Calculator
A1C is a percentage; the glucose meter gives milligrams per decilitre. The estimated average glucose formula translates one into the other so the two numbers can be compared directly.
Estimated average glucose (mg/dL)
116.89
- Average glucose (mmol/L)
- 6.4873
- A1C on the IFCC scale (mmol/mol)
- 38.798
Values update as you type. This calculator covers the single scenario its formula assumes — see Common Mistakes for what it leaves out.
The formula this calculator uses
eAG = 28.7 x A1C - 46.7
- eAG
- Estimated average glucose in milligrams per decilitre
- A1C
- Glycated haemoglobin as a percentage of total haemoglobin
- IFCC
- The same A1C expressed in millimoles per mole, the newer standard
How to check the result by hand
- 1
Take the A1C as a percentage
Laboratory reports usually give it to one decimal place, such as 5.7 per cent. Make sure you are not looking at the millimoles per mole figure, which sits in the thirties and forties.
- 2
Multiply by 28.7
5.7 times 28.7 is 163.59. This sets the slope of the relationship, so each extra percentage point adds about 29 milligrams per decilitre.
- 3
Subtract 46.7
163.59 minus 46.7 is 116.89 milligrams per decilitre. Both constants belong together; using the slope without the offset gives a badly wrong answer.
- 4
Convert to millimoles if you need it
Divide by 18.0182. 116.89 divided by 18.0182 is about 6.49 millimoles per litre, which is the unit most meters outside the United States display.
- 5
Compare against your meter average
A meter average near 117 milligrams per decilitre should correspond to an A1C close to 5.7 per cent. A large gap in either direction is worth raising with your clinician.
For worked examples, common mistakes and the limits of this formula, read the full How To Convert A1C To Average Blood Sugar page.