I’m attempting to modify this for an Extra Large Swiffer for my aunt. The measurements of the Swiffer are 16.5x5 inches. I chained 61 stitches to start because it was about an inch shorter than 16.5. This worked, but could have been a little longer - but only one or two stitches. I also made button straps to help keep it on since it’s so long. My aunt says that it works better than the store bought replacements!