Measure the height and width of the back of the chair. Measure the width and depth of the chair’s seat. Measure the height of the chair from the top of the seat to where you want the skirt to end. Measure around the chair just below the seat to determine the skirt size. Add 1 inch to each measurement to allow for 1/2-inch seams.
Cut the geometric upholstery fabric to the measurements determined in Step 1 using fabric scissors. Mark the backside of the fabric with a fabric pen to indicate each piece. You need two pieces of fabric for the back, one piece for the top of the chair and one piece of fabric for the skirt.
Place the two pieces of fabric for the back of the chair right sides together on your work surface. Secure the pieces of fabric together using straight pins placed 1/2 inch in from the edges of the fabric. Sew a 1/2-inch seam using a sewing machine, leaving the side that will rest along the seat unsewn. Remove the straight pins.
Fold one of the long edges of the skirt pieces over 1/2 inch. Secure it in place with straight pins. Sew a 1/2-inch hem using a straight stitch on the sewing machine. Remove the straight pins.
Place the seat piece of fabric on the seat with the right side down. Turn the skirt fabric so that the right side of the fabric is facing the chair. Wrap the skirt fabric around the chair with the hemmed edge hanging down. Pin the unhemmed edge to the seat piece using straight pins, right sides together. Place the pins 1/2 inch in from the edge. Do not attach the part of the skirt that goes around the back of the chair to the seat fabric.
Slip the chair back piece from Step 3 onto the back of the chair with the wrong side out and the right side facing in. Pin the chair back fabric to the seat fabric using a 1/2-inch seam. Pin the skirt fabric in the back of the seat to the chair back fabric using a 1/2-inch seam. Pin the loose ends of the skirt fabric together. Carefully slide all the fabric off the chair.
Sew along the straight pins to attach the seat, skirt and chair back together. Remove all the straight pins. Turn the fabric right side out before sliding the completed cover on your chair.