Seat Height / Leg Length: Measure from the userís heel to the popliteal fold and add 2 inches to allow clearance of the footrest. Average adult size = 19.5 to 20.5 inches. The bottom of the footrest is 2 inches from the floor. You can fit 2-3 fingers under the distal thigh (between the thigh and the seat)
Seat Depth: Measure from the userís posterior buttock, along the lateral thigh to the popliteal fold; then subtract 2 inches to avoid pressure from the front edge of the seat against the popliteal space. Average adult size = 16 inches
Seat Width: Measure the widest aspect of the userís buttocks, hips or thighs and add 2 inches. This will provide space for bulky clothing, orthoses or clearance of trochanters from the armrest side panel. Average adult size = 18 inches
Back Height: Measure from the seat of the chair to the floor of the axilla with the userís shoulder flexed to 90, then subtract 4 inches. This will allow the final back height to be below the inferior angles of the scapula. Average adult size = 16 Ė16.5 inches
Armrest Height: Measure from the seat of the chair to the olecranon process with the userís elbow flexed to 90, then add 1 inch. Average adult size = 9 inches above the chair seat
Wheelchair Passage Width: The minimum clear width for single wheelchair passage shall be 32 in (815 mm) at a point and 36 in (915 mm) continuously (see Fig. 1)
More measurements and downloadable format available at :