Try this web page:
https://www.hba1cnet.com/hba1c-calculator/
Put your 6.2 mmol/L in the bottom right hand box and your HbA1c in mmol/mol will appear in top left box.
42-47 pre-diabetic
>47 diabetic
6.2 will indicate 37 normal
However, once diabetic it is easy for it to creep up again...