I have the iPhone app, too, but my good friend here on the board will figure out how much yardage I need on her same app. I am calculator illiterate. I can't do math so the calculator isn't helpful. I one time was able to find out how many strips of fabric I needed for binding, all by myself. But my friend is so good to me that she always figures out what I need. Everyone needs a friend like mine. She's perfect!!