how to determine proper fit in a wheelchair

Measure Seat Width and Depth
Determine seat width by measuring the person’s hips from one end to the other, in a straight line. Then add two inches to this measurement to select a proper wheelchair seat width.
Determine seat depth by measuring from the back of the hip to the back of the knee of the person while seated. Then, subtract one inch from this measurement to choose the correct seat depth.

Selecting the Arm Type and Height
Full-Length Wheelchair Arms: These are best-suited for people who will be frequently doing stand-up pivot transfers. The full-length arm provides the proper support a person needs to help push themselves up to stand.
Desk-Length Wheelchair Arms: These are recommended for when a wheelchair-bound person will want to be comfortable sitting at a desk or table. The shorter arms allow them to get closer to the table edge.
Arm Height: The height of the wheelchair arm can vary. Measure from the elbow to the seat of the chair while the person is holding their arms up with their elbows bent at a ninety-degree angle. When available, height-adjustable arms are recommended.

Weight Considerations
Wheelchairs are built to accommodate certain weight limits. Make sure you know the person’s weight so that you can fit them to a wheelchair that can support them safely.
Some people in wheelchairs fold up their own chairs and place them in their cars so that they can travel in a regular car seat. In fact, many people who use wheelchairs still have the ability to drive. Therefore, take into account the person’s upper body strength when selecting a wheelchair. Weaker patients will require lighter wheelchairs.