Place the pattern paper over the rocking chair. Cut templates for the back and seat of the chair, adding a 1-inch seam allowance on all sides. Measure your patterns to determine how much fabric you need for the project.
Lay the templates over the fabric and cut accordingly. Use a yardstick to assist you with cutting straight lines and a carpenter square to create right-angle corners.
Place the pieces of fabric on the rocking chair and pin them to the cushion. Ensure that the material is smooth and has no creases or crinkles.
Pin the seams for two individual pieces together and remove these pieces of fabric from the chair. Sew the two pieces on the wrong side and pin back to the rocking chair. Repeat this procedure until you have sewn all the pieces of fabric together. Place the new slipcover over the old cushion.