Most datacenters and hosting providers use the “95th Percentile” or "burstable billing" method, while others utilize Average Usage Billing. Throughout the month, these host take measurements of your bandwidth usage every 5 minutes. At the end of the monthly cycle, these measurements are added together and we divide this number by the number of measurements taken. Measuring of bandwidth in this manner results in a true “average” usage reading for your bandwidth bill.
Using this method allows hosts customers to take advantage of the natural peaks and valleys that occur from day to day bandwidth usage.