What does credit card ‘interest-free days’ mean?
Usually a credit card will give you up to 55 interest-free days to repay any purchases you make on the card. Some cards offer up to 62 days. After this period, your debt will begin to accrue interest.
However, not every purchase gets 55 days interest free. That depends on when the purchase is made during the monthly billing cycle. The interest free period usually begins on a similar day each month so pay your card off in full every month to make sure your interest-free days apply.
Source: Herald Sun