As others have said, jelly rolls are 2 1/2 inches wide and 40-42 inches long. Keep in mind they can be cut in a variety of ways for quilt patterns, not just for straight strip sewing. They are the standard size for binding strips, but to me that is not an economical way to use them. The jelly rolls I have purchased are name brand manufacturers/pattern and so are pricy and you can cut binding strips from less expensive fabrics. I bought charms and jelly rolls when I first started quilting as it was an easy way to get coordinating fabrics and I wasn't confident in selecting fabrics. But now I would never buy them and really enjoy the fabric selecting process.