A generously proportioned "quarter yard" of fabric that measures 18" x 22". To understand this you need to do a little math. Fabric is measured in yards. A yard is 36". When you ask your fabric store to cut a yard of fabric, you get 36" by the width of the fabric. Quilting cottons are usually 44" wide. So, if you buy a yard of quilting cotton, you'll have a cut piece that measures 36" x 44". Now, if you'd stepped up to the counter and ordered a quarter yard of fabric, you'd get a piece that is 9" (36" divided by 4) by 44". But a Fat Quarter is actually a full quarter of that original piece we got when we ordered our single yard of fabric (36" x 44"). If I divide that original piece (36" x 44") into four equal pieces, each one will be 18" x 22". A Fat Quarter.