It kind of depends on what pattern you pick and how many strips came in your jelly roll. Also, the more seams you have in your top, the smaller it will be. I made a zigzag quilt with 2 jelly rolls (40 strips of fabric in each roll) that measures 68" x 68". A typical jelly roll race quilt measures about 50" x 64". If you think you need more fabric, you can always expand and supplement with a neutral-colored jelly roll, or strips of complimentary fabric from your stash.
