This should help ....
Scraps are Perfect for This Pretty Block - Quilting Digest
It gives the amount needed for one 15" block (finished size).
Decide how many blocks you want, and then, you're off and running to determine your yardage requirements.
A perfect quilt to use scrappy leftovers!
Be sure to keep your stitch and flip cut offs, as they will give you a whole bunch of HSTs for another project. I usually do their seam before I do the trimming, so that they stay attached!