I don't often get "extra", but it does sometimes happen. As someone has previously posted, I almost always buy extra just to make certain I don't run short on the fabric. I sometimes make the error and miscalculate -- my bad. I do at least want to get what I pay for, and if the extra is a sizeable amount, I will point it out and pay for the extra fabric. I can almost always use the extra fabric for potholders, etc. I always make certain I buy plenty of fabric for backing -- if I'm making a solid back, I don't want to have to piece it. By doing so, I end up having large enough backings that I seldom have to buy backing (white muslin) fabric for baby quilts.