If you have a zero balance on your credit card and you charge an item Float is the time period after you charge an item until your statement prints. Your payment becomes due on the statement date.
After the statement prints you have a minimum of 21 days until the payment is past due, this is your grace period. If you paid you Credit Card in full last month, and you pay in full within the grace period you will not be charged interest.
If you do not pay within the grace period interest will be calculated from the statement date which is 21 days earlier!
That is right you do not get a grace period or float on your purchases if you did not pay off your credit card in full last month.
Taking advantage of float and the grace period is really easy. Always pay in full and always make your payment on time which is withing 21 days of your statement printing.