I use the Robert Kaufman quilt calculating app all the time. I don't know if I missed it before or there was an update, but I just noticed that the app now has calculations in metric or inches (at the bottom of the calc screen.

This is a free quilt app that you can get from the Google Play store. For those of you who needed the metric system, it's available. (lol, I only discovered this when I got metric measurements and thought, what the heck? I need inches!