Measuring a wheelchair’s width involves two distinct dimensions: internal and external. The internal measurement, or seat width, ensures proper fit for the user’s body, which is fundamental for comfort, posture, and skin health. The external measurement, or overall width, determines the chair’s physical footprint and dictates its ability to navigate through doorways and other architectural barriers. Understanding both dimensions is necessary to select a device that is both ergonomically sound and compatible with the user’s daily life.
Seat Width Measurement
The correct seat width is determined by measuring the user’s body at its widest point while they are seated on a firm, flat surface. This point is typically across the hips or thighs, and the measurement should be taken with the user wearing the clothing they normally use, as different fabrics or layers can slightly alter the dimension. It is important to use a rigid measuring tool or two blocks placed vertically against the hips to ensure an accurate, straight-line distance, avoiding the common error of wrapping a tape measure around the body.
Once the widest body measurement is established, a small allowance must be added to prevent friction and pressure sores. Experts generally recommend adding approximately one to two inches to the raw hip measurement, which provides just enough clearance for movement, clothing, and slight shifts in position. A seat that is too narrow will cause pressure against the hip bones and thighs, potentially leading to skin breakdown or discomfort. Conversely, a seat that is too wide can compromise postural stability, making it difficult for the user to maintain a midline position and reach the hand rims for propulsion.
The seat width of an existing or new wheelchair is measured horizontally from the inside edge of the seat frame on one side to the inside edge on the other, often referred to as the width between the side panels or armrests. This internal frame measurement must correspond closely to the user’s body measurement plus the clearance allowance. For a chair with a flexible sling seat, the measurement is taken at the widest point of the upholstery, and it is common for seat widths to be manufactured in two-inch increments, such as 16, 18, or 20 inches.
Overall Width Measurement
The overall width, or external width, is the maximum horizontal distance from the outermost projection on one side of the assembled wheelchair to the other. This dimension is important for assessing environmental accessibility. For a standard manual wheelchair, this widest point is typically the distance between the outside edges of the two rear wheels, including the tires or hand rims.
This total width must be compared against the clear opening of doorways and confined spaces. While standard manual wheelchairs typically range from 24 to 32 inches wide, the Americans with Disabilities Act (ADA) standard for a minimum clear doorway width is 32 inches. A slightly wider opening, such as 36 inches, is often recommended to allow for the hand clearance needed to propel a manual chair without scraping the hands.
Power wheelchairs are generally wider than manual chairs because their overall width is defined by the base, which houses the motors, batteries, and drive wheels. The widest point on these devices may be the anti-tip wheels, the drive wheel casings, or the joystick and armrest housing. The average width for a power chair is typically broader, ranging from about 24 to 33 inches, making it especially important to verify this external dimension against all common access points.
Accounting for Chair Variations
Design variations can significantly alter both seat and overall width measurements. For manual wheelchairs, the angle of the rear wheels, known as camber, increases the overall width to enhance lateral stability and maneuverability. Camber is measured in degrees; increasing the angle by two degrees typically adds about one inch to the total footprint, which is critical when navigating narrow spaces.
Folding wheelchairs introduce a second external measurement: the folded width, which is the dimension across the chair when it is collapsed for transport or storage. This folded width is generally much smaller, often around 11 to 14 inches for a manual chair, and is the relevant number for fitting the device into a car trunk or a small closet. This measurement must be taken with any removable components detached, such as the footrests or quick-release wheels.
Internal variations, such as the addition of specialized seating components, affect the effective seat width available to the user. Thick seat cushions, which are added for pressure distribution and comfort, will reduce the vertical space but do not change the frame’s measured seat width. However, components like custom lateral supports, which are positioned on the sides of the torso to improve posture, directly decrease the usable width, meaning the user’s body must fit within the space between the supports, not just the frame.