Make the Seat Cushion
Measure the length and width of the chair seat. Cut a piece of batting to these dimensions.
Add 1 inch to both measurements taken in Step 1 and cut two pieces of fabric to these dimensions.
Place one fabric piece onto a work surface with the wrong side facing up. Place the batting piece on top of the fabric piece and place the other fabric piece on top of the batting with the right side facing up. Pin these layers to secure them.
Sew around the edge of the fabric layers with a 1/2-inch seam allowance.
Position the bias tape at the edge of the sewn seat cushion with the center fold at the edge of the fabric and the edges of the bias tape surrounding the seat cushion edge on the top and the bottom. Turn under the raw edge of the bias tape, and pin the bias tape to the edge of the seat cushion to finish the raw edges of the seat cushion. Cut the excess bias tape off when the bias tape has been pinned all the way around the edges, leaving 1/2 inch for turning under the raw edge of the bias tape on the other end. Turn under the end of the bias tape.
Stitch the bias tape to the seat cushion by sewing 1/2 inch from the edge all the way around the seat cushion.
Repeat steps 1 through 6 to make as many dining room chair cushions as needed.
Make the Seat Skirt
Determine how long you want the skirt of the cushion to be. Six inches would be an average length of a seat skirt. Add 1 inch to this desired length for seam allowances.
Measure around the perimeter of the seat. Assuming the dining chairs have a back, begin measuring at one side edge at the back and measure around the front of the chair to the other side edge at the back. Add 1 inch to this measurement. Double this measurement.
Cut a piece of fabric with a width that is the dimension determined in Step 1 and a length that is the measurement figured in Step 2.
Turn under 1/2 inch along each long edge and press this fold. Sew 3/8-inch from the pressed fold to hem both long edges.
Gather one long edge of the skirt piece with long machine basting stitches. Do not pull the stitches to gather yet.
Repeat steps 3 through 6 to make as many fabric skirts as needed for the chair cushions.
Finish the Slipcovers
Position the gathered skirt piece onto the seat cushion so that it will begin at the side edge where the back of the chair is and will wrap around the perimeter of the seat cushion to the other side at the back of the chair. Place the skirt piece so that right side is facing out.
Pull the gathering stitches to fit the skirt piece to the seat cushion. Pin the skirt piece to the seat cushion when you have adjusted the gathers so that they are neat and even.
Sew around the edge of the seat cushion to attach the skirt piece to the seat cushion.
Repeat steps 1 through 3 to attach all of the skirt pieces to the seat cushions.
Position the slipcovers onto the dining room chairs so that the skirting is on the sides and front of the chairs and the skirting drops down over the edges of the seats.