Hi, all!

Is there a rule of thumb for sewing darts? I am making microwave bowl cozies, and wondered. As a non-sewer (or a sewer of quilts and not knowing clothing rules), I wondered if there was a rule of thumb. I have a 13 1/2" bowl. I made one with a 1" side and 3" length dart. I felt it was still too "flat". Do I need to go out to 1 1/2" or go in and make the dart smaller? My brain isn't working!