Write down the measurements of the inside back, outside back, the width and height of the arms and the sides of the chair.
Double the measurements and add 1-inch for a seam. This is yardage of material necessary for the slipcover.
Draw an outline of the chair on graph paper to use as a reference. Draw the outline from the graph paper to the inside of the fabric with a washable marker. This will give you a slipcover pattern.
Cut the individual pieces of the pattern from the fabric. Label each piece with a letter to indicate how they fit together.
Place the cut pieces of fabric against the chair and secure them with pins. Create a crease on the pinned seams with an iron.
Sew the inside of the creases together with the sewing machine. Fold the slipcover so the fabric is now right-side out.