The distance from the back of the body to the inside of the knee, minus a minimum of two inches (with some individuals preferring more to accommodate for hand placement when lifting their leg).
Measured from the seat base to the top of the chair back.
The angle at which the toes extend away from the body, measured horizontally, affects the turning radius of an electric power wheelchair. A tighter angle allows for tighter turns and a smaller turning radius, and it also dependent on the knee's range of motion.
Determined by the widest point of the body from knee to hip, plus an inch to ensure room to move. Consider bulkiness of clothing, particularly a heavy winter coat, if relevant.
From Seat to Floor
To measure the proper length for a footrest on an electric power wheelchair, the distance from the back of the knee to the sole of the foot is measured and the thickness of the cushion when compressed is subtracted. A minimum of two inches is then added for footrest clearance. It is uncommon for users to manually propel electric power wheelchairs, so the additional two inches for footrest height is typically included.