First of all, I bought 1 1/3 yards of two coordinating fabrics. I had a little bit left over but not a whole lot. I thought it would be better to be safe than wish I had more. When I got it home I measured it to be the size I wanted. I chose to do it about 38″x40″. Depending on your car seat you may want to make it a different size. I figured this would work well for mine.