A pillow-top ottoman is an ottoman that looks like it has a loose pillow on top. Sometimes the faux pillow even will have a button in the middle. Making a slipcover for this type of ottoman is a little more complicated because you also will want it to maintain the style. This means that your finished cover will resemble the pillow top and have its top and skirt joined together.
Wash and iron your fabric so that it will not shrink. Measure the width of the top of the ottoman. Measure the height of the pillow from its top to the base. Add twice this height plus 6 inches to your width measurement. Measure the ottoman's length. Add the length to twice the height plus 6 inches for your length measurement. Cut your top cover.
Place your cover face down. Measure from the top edge using your height measurement and 2-1/2 inches. Draw a line at this measurement parallel with the top edge. Measure up from the bottom edge and use your same height and 2-1/2 inches. Make a mark. Draw a line with tailor's chalk parallel with the bottom edge. Repeat for both sides. You should see two chalk lines that form a square at each corner of the fabric. Cut out the squares along the chalk lines at each corner.
Place the fabric's right sides together and pin a 1/2-inch seam allowance along each corner. Sew your corners. Turn your cover right side out and fit it to the ottoman. If you want to round the corners for a better fit, taper the top corner of each corner seam until the cover fits how you prefer. Leave the cover on the ottoman.
Measure the ottoman's perimeter and add 4 inches. Cut a strip of fabric to this length that also is 4 inches high. Cut a 1/4-inch thick cord to this length. Fold the fabric, with face side out, in half lengthwise inserting the cord in the fold. Sew a tight seam along the cord.
Pin your wrapped cord to your cover at the height of the joint between the ottoman base's and the pillow. The cord side should face up and the raw fabric side should face down. Overlap the end of the cord half an inch and remove the cover. Sew the covered cording onto the cover top. Place your cover back on the ottoman.
Add 33 inches to the perimeter measurement, plus 1 inch per joining seam. A joining seam is where you join pieces of fabric together to make a longer piece of fabric. Measure the height of the ottoman from the bottom of the cord to the floor and add 1 inch for seams and hems. Cut your side fabric.
Overlap your left side corner with 2-1/2 inches of side fabric. Fold under half an inch of the top edge and pin the fabric to the top cover. Wrap the fabric 2 inches around the corner with the top edge still folded under the half an inch and pin. Fold the fabric back to the left 2 inches (this should take you to the corner) and pin the fabric. Take the fabric along the ottoman side with the top edge folded under and pin every 4 inches to 5 inches. Stop pinning 4 inches from the right corner.
Find the spot on the fabric where it will turn the corner. Pin that spot into the side fabric. Continue 2 inches to the right of that spot and fold the fabric under and to the left. Line the under fabric top edge up with the upper fabric and pin through to the cover. Continue 2 inches to the right to the corner, and 2 inches past the corner. Pin the side fabric to the cover. Fold the side fabric back 2 inches to the corner and pin through to the cover. Continue to the next two corners repeating each pleating process at the corners.
Pin the side fabric edges together where it joins once you have gone around the ottoman. Remove your cover and sew the side fabric edge seam first with a 1/2-inch seam allowance. Sew 1/4 inch from the bottom of the cord and attach your skirt to the top cover. Continue around the ottoman. Place the cover on the ottoman and pin your length. Sew your hem all around. Iron your pleats at each corner.