Locate the center of the rails (channel) as shown in Pic. 1 and 2
Towards the top part of the chair’s sling, place the tape measure in the center of one rail and measure across to the opposite rail as shown in Pic. 3
Towards the edge of the chair’s seating sling area, place the tape measure in the center of one rail and measure across to the opposite rail as shown in Pic. 4
Place the tape measure at the very top of the sling rail (don’t include end cap) and measure following the curve (if any) carefully until the edge of the bottom rail. Important: Use the rail as your guide and not the sling fabric as shown in Pic. 5