Hmmm...that's a good question! And, I'm not sure!
I tend to buy lots of it, because I use it a lot, so I didn't even think to keep track. If I were to guess, and don't hold me to this if you run out,
I would say about 24 of the 9 x 12 sheets. The Steam a Seam can be spliced together easily, so you can make use of all your scraps.