Use a tape measure to determine the width of the chairs you want to cover.
How to make dining room chair covers for the seat.
Then measure up the back of the chair from the floor to the top down the front of the backrest along the edge of the seat from back to front and from the seat down to the bottom of the legs.
If you have an oversize dining table and chair set and your dining room chair is wider you may consider using 60 inch wide fabric to guarantee adequate coverage.
You need about 3 yards of 45 inch wide fabric to cover one standard size dining room chair.
Sew a slipcover out of fabric.
Pin the front fabric piece to the back pulling it taught to ensure a snug fit.
For this project the chair was 44 inches high x 20 inches wide x about 22 inches deep.
How to re cover a dining room chair.
Then pin around the chair seat and connect it to the fabric over the chair back.
If you are making a simple cover with no cushion cut the fabric to the size needed and also cut fabric to be the liner on the bottom of the seat cover.
Cut new fabric place your foam and seat on top of your new fabric.
Take measurements of the chairs.
Add another inch if you plan to make cushioned seats.