Can't help you with predicting data usage....But I down loaded a app. from " Goggle play " called " My Data Manager" . It keeps track of your data usage by hour, day, and month. You can check it as often as you like. You could view you data amount then log in for a set time and re-check the new amount and subtract the amounts to determine the amount of data used. You could then use that amount as a average.<div><br></div><div>I have to keep a good watch on my usage as I am in a plan...Down loading songs and videos really eats the data up fast. I used almost 1 gigabyte in a day one time. Also for me tethering from my phone to my laptop uses a LOT of data. </div><div><br></div><div>BTW...My Data Manager is a free app.</div>