How do I calculate the length of my strips? Answer: The 40 minute quilt is made up from scrap strips, each cut 2.5" wide by whatever length your material is. Valerie joined lots together to get her quilt top. In order to work out how long you want you need to think about the size you want to create and will there be borders? - if not then the calculation goes like this: For each strip sewn it will become 2" wide and if you want it to be 40" in the other direction then just divide the size - say 60" by 2 = 30 strips at 40 This can also be made with a ready-bought jelly roll - just look at the number of strips in it.