Measure the rail of the sling chair using the measuring tape. Start at the bottom of the chair and work your way up to find the length of the sling rail. Make sure to place the measuring tape directly on the rail and hold it firmly while you work your way up to get a correct length measurement.
Start about 4 or 5 inches down from the top to get the width measurement. Jot down this width measurement.
Take a couple of other width measurement from different parts of the chair as well. Take one at the seat and also at the halfway point if you have a lounge sling chair.
Average the width measurements together if they vary a little to get the most accurate measurement for the width of your sling chair.
Purchase a new sling with these measurements.
Remove the ends caps from the chair. Use a flat head screwdriver if necessary to pry them loose.
Unbolt the side rails using a wrench.
Remove the old sling.
Work on one side at a time and insert the plastic spine into the casing of the sling. Slide the fabric and the sling into the rails.
Replace all the bolts and tighten them down to tighten the sling. Replace the end caps.