Remove a strip of the longest webbing. The webbing will be secured with a nut at both ends where it attaches to the frame. Remove the nuts and unwind the webbing from the chair. Lay the webbing flat and measure the length. Multiply the length by the number of web strips. Write the number down.
Remove a strip of the short webbing. Find the total length for this webbing the same way you did for the long strips. Write the number down.
Add the two numbers together for the total number of feet it will take to cover the chair.
Measure the width of the original webbing and write it down.
Purchase the webbing at a discount store or home improvement center. The width of the webbing and the amount of webbing will be labeled on the package.