Waysact is unlikely to use more than 40 or 50mb per month - it's a very lightweight app that only takes a few hundred kb to download all the code and a typical form to the browser to start work. Each pledge is at most 60kb, and there's 1024kb per mb. An iPad may be used for other things though - it's a very useful fundraising tool on the street. These other things can often involve charity creative, imagery and video, and this is very data hungry. We'd normally recommend 1GB per month is sufficient but do check what happens when that limit is reached and put in place controls appropriately to ensure you don't have issues. Remember Waysact *can* work offline but requires an internet connection to log in.