HbA1c conversion table

Wondered is it possible to predict HbA1c from finger prick results came across this chart, but don’t know how accurate it is. When I was diagnosed my fasting blood glucose was 14.9 and my HbA1c 110, on my most recent HbA1c of 39 my finger prick results on my gluco meter were between 5.0 to 6.0, but wasn’t given a fasting blood glucose for this test nor did I fast prior to it.

found this chart wondered how accurate it is

I’m finding my average recently has been 6.0, this means according to the chart I found a HBA1C of 42 but by the calculator on this site 35.9.
I’m confused is mmol the measurement of finger prick results?

I found this on accu chek which explains it now

https://www.accu-chek.co.uk/tools-and-resources/average-blood-glucose-and-the-hba1c-test