When choosing a backing width, you’ll want to measure your quilt top and add 6-12 inches to determine your backing size needs. This allows plenty of room for seams and adjustments. I have faced situations where undersizing the backing resulted in a feeble final appearance due to pulls and bubbles. Play it safe with extra width. For most large quilts from king to queen size, 108″ cotton or blended backing should suffice. California king and above may require 119″ or 140″ backing for a perfect wall-hanging fit. Extra large pieces like those spanning multiple king beds � require the widest backings for sleek results.