Measure the length of the wingback chair from the floor in front, over the seat cushion, up the backrest and down to the floor behind the chair. Increase the measurement by 6 inches, and write it down.
Measure the width of the wingback chair from one armrest and across the seat to the opposite armrest. Increase the measurement by 2 inches, and write it down.
Measure the width of the wingback chair back from the front-most point of the wing portion to the rear edge of the chair and the height from the armrest to the top of the chair. Increase both measurements by 2 inches, and write them down.
Measure the height of the wingback chair arm, starting at the floor below the arm, over top of the armrest and stopping at the seat cushion. Increase the measurement by 12 inches, and write it down.
Measure the width of the wingback chair body from the front edge of the seat to the back edge of the chair. Increase the measurement by 2 inches, and write it down.
Sketch the five pattern pieces with their measurements on a piece of paper; one body piece using the measurements from Step 1 and Step 2, two arm pieces using the measurements from Step 4 and Step 5 and two wing pieces using the measurements from Step 3. Sketch a picture of the chair to help you visualize how to sew the pieces together.
Pin the bottom edge of the wing pieces to the rear top edge of the arm pieces, matching the right sides together. Sew the pieces together with a 1/2-inch seam to create a chair-shaped piece for both sides.
Pin the long edge of the body piece to the outer edge of the side piece you just sewed together. Match the right sides together, and sew a 1/2-inch seam. Repeat this process on the other side of the body piece with the second side piece, and sew them together with a 1/2-inch seam.
Pull the cover over the chair to verify the fit. Adjust the seam's depth around the wing area, if needed.
Cut off excess fabric around the bottom edge of the cover if it hangs longer than 1/4 inch onto the floor. Take the cover off the chair, fold the bottom edge 1/4 inch to the wrong side of the cover, and pin to hold. Fold the edge under another 1/4 inch, and sew to secure in place.