If I'm just 'gathering' fabric, I buy in 1/2-yard increments. If I have a loose Plan for the fabric (i.e., I know who it is for but don't have a pattern), then closer to 1-yard. And then, of course, there are those irresistible fat quarters & precuts. Except for flannel - I back all of my sofa & lap tops in flannel, so I buy 3-5 yards at a time.