I made one recently, would be about 36" x 44" without the end borders. I used 4" finished size squares, and it took 99 squares, in 7 different colors (but I used scraps so it was more than 7 different fabris). I made a tutorial and put it here:
http://www.quiltingboard.com/t-45544-1.htm
I suggest graphing it out, too.