You will need approximately  1 & 1/4 yards of two different colors of material.  This amount is based on your squares being 12″ big and using 35 photos.   Adjust the amount to fit your needs.  The way I came up with this formula was to take the number of photos you want on your quilt and that will tell you the number of squares  you will have.   After know the number of squares, and lay it out on paper, you can then take the number of squares and multiply it by 12″ (or what  ever size you want your squares to be).  Most materials are 45″ wide, so plan the amount you buy on this formula.   

You will also need 2 &1/2 yards of  white material.  This is what you will iron your transfer pictures on to.  It is very important that you get “white” because other wise your photos will look muddy or just plain weird.  I buy just a plain white flat sheet for this, just make sure that it is of average or better thread count so your photos won’t look too scratchy.  You can always find a way to use the rest of the white material.  Your next quilt!!  What a great idea.  I make my white squares 9″, that way  I have a 3 inch border of the colored material around each picture.  Remember to allow 1/4″ for seam allowance on each square.