As an application, Yahoo! Go 3.0 is free of charge. Downloading and using Yahoo! Go 3.0 is a different matter. You would need to know how much your network carrier charges for data and how much data you use. When you exit Yahoo! Go 3.0, it shows how much data was used for that session.

As a general rule, keep in mind that large data items are photos and mail attachments. If you are using very many of these, you should find out how your network carrier accounts for the large data traffic on your bill.