I used jelly rolls, so mine were all 2.5" by 44". You can vary the width of the strips. If you google "Sonja's Windows quilt" you will see what it looks like with varying width of strips. This is actually where I got the idea for my quilt from, although I found out later that it's very similar to the 3 Dudes quilt pattern, only they used 4 strips instead of 5, and didn't alternate contrasting fabrics.
Wait - when you say "width" are you referring to the 2.5" measurement, or the 44" width of the strips I used? You can use shorter strips, like from your stash. 5 strips at 2.5" wide will give you a section that is 10.5" tall. So you need strips that are at least 10.5" long, because they need to be square when you sew them together. Hopefully that makes sense?