Wheelchair Measurements: Seat Width, Depth, Height and Footrests

Why fit matters

A well-fitted wheelchair supports the pelvis, spreads weight evenly, keeps the feet and legs in a good position and allows the user to reach the wheels and to transfer in and out safely. A poorly fitted chair does the opposite.

• Too narrow squeezes the hips and thighs, causes pressure and makes dressing hard.
• Too wide leaves the person unsupported, makes them lean to one side, makes it hard to reach the wheels and makes the chair too wide for doorways.
• Too deep presses behind the knees and makes the person slide forward.
• Too shallow gives too little thigh support.
• Footrests too low or too high put pressure on the thighs or the back.
• Armrests too high or too low make shoulders hunch or slump.

For anyone who sits for hours, a good fit is the first line of defence against pressure sores; see pressure care in a wheelchair.

Before you measure

• Ask your parent to sit in a firm, flat chair, such as a dining chair, not a soft sofa, with hips well back, feet flat and knees bent at a right angle.
• Make sure they wear normal clothes and shoes, because thick clothes add width.
• Use a flexible tape measure and a rigid ruler or a book.
• Record measurements in centimetres or inches, and write them down.
• If your parent leans or has a curved spine, ask a therapist to help.
• If they will use a cushion, measure with it in place, or allow for its thickness.

The six key measurements

### 1. Seat width

Measure the widest part across the hips or the thighs, whichever is wider, while sitting. Add about 2.5 cm (1 inch) on each side, to allow for clothing and to give room to move. So add about 5 cm (2 inches) in total. A person whose hips measure 40 cm needs about a 45 cm seat.

Common chair widths are 16 inches (40 cm), 18 inches (45 cm) and 20 inches (50 cm). Choose the one that is closest to the measurement without being narrower. Check that the chair's outside width, which is wider than the seat, can pass through your doorways. A typical standard chair is 60 to 65 cm wide overall.

### 2. Seat depth

Measure from the back of the buttocks to the back of the knee, along the thigh. Subtract about 2.5 to 5 cm (1 to 2 inches), so that the front edge of the seat stays clear of the back of the knee. The thighs should be supported for most of their length but the knees should be free to bend.

### 3. Seat height

Measure from the floor to the back of the knee, with the foot flat, then add the footplate clearance, about 5 cm (2 inches), and the thickness of the cushion. Standard seat height is 45 to 50 cm. A lower seat suits foot-propelling users, who push themselves with their feet; a higher seat suits transfers.

### 4. Footrest length (lower leg length)

Measure from the back of the knee to the sole of the foot while sitting. The footrests should allow the thighs to rest on the seat cushion, with the feet comfortably supported and about 5 cm (2 inches) clear of the floor. If footrests are too low, the thighs lift off the seat and pressure moves to the buttocks; if too high, the knees are pushed up and weight shifts onto the tailbone.

### 5. Back height

Measure from the seat to the bottom of the shoulder blades for active users who propel themselves, so the arms can move freely. For people who need more upper body support, measure to the top of the shoulders or the head. People who lean or cannot hold themselves upright may need a higher or tilted back. A therapist can advise.

### 6. Armrest height

With the elbows bent at about 90 degrees and the arms resting at the sides, measure from the seat to the bottom of the elbow, and add about 2.5 cm (1 inch). Armrests too high push the shoulders up; too low make the person lean sideways.

Other measurements and checks

• Weight. Check the chair's user weight limit against your parent's weight.
• Chair width and folded width. For doors and cars.
• Overall length. For lifts, vehicles and tight corners.
• Turning space. A manual chair needs about 1.5 metres to turn around.
• Door widths. Measure all doors the chair must pass through. Add some room for the hands on the wheels. See buying a wheelchair in India.

Reading a chair specification

Every chair has a data sheet. Check:

• Seat width and depth (and whether adjustable).
• Seat-to-floor height.
• Back height.
• Footrest range.
• Armrest type and height.
• User weight limit.
• Overall width and folded width.
• Chair weight.
• Wheel and castor size.

Note that a "20-inch" chair may have a seat width of 20 inches but an overall width of 26 inches. Compare like with like.

Adjustable chairs

Some wheelchairs adjust: seat width, depth, back height, footrest length, armrest height. These suit people who will be in the chair long term, whose needs may change or who share a chair between family members. Adjustable chairs are heavier and more expensive. Rental chairs are often fixed standard sizes.

Cushions and measurement

A cushion adds height, which affects armrest, footrest and doorway clearance. A 5 to 10 cm cushion raises the seat, so factor it in. A pressure cushion changes how a person sits; fit the cushion and then check posture. See gel cushions for pressure relief and cushions for wheelchair users.

Signs of a poor fit once sitting

Check these after your parent has been in the chair for a few minutes.

• Sliding forward or slumping, which suggests the seat is too deep, too soft or the footrests are wrong.
• Leaning to one side, which suggests the chair is too wide or the person needs lateral support.
• Marks or redness on the hips, thighs or behind the knees after sitting.
• Knees higher than hips, meaning the seat is too low or the footrests too high.
• Feet hanging or dragging, meaning footrests too high or too low.
• Shoulders hunched, meaning armrests too high.
• Struggling to reach wheels or hand rims.
• Pain in the back, hips or shoulders.
• Difficulty breathing or swallowing, which can come from slumped posture.
• Skin changes, which need urgent attention; see pressure ulcers: stages, wound care and prevention.

Special situations

A person who has lost weight or gained weight. Re-measure; a chair that fitted may now be too wide or too narrow.

A person with swollen legs. Footrests that elevate the legs may be needed; ask a therapist.

A person with a single leg or amputation. Special footrests and anti-tippers; see amputation and prosthesis in older adults.

A person with spinal curvature or stroke. May need a custom or tilted seat. Seek professional help.

Two users. A chair shared by a taller and a shorter person will fit neither; adjust or buy separate chairs.

When to ask a professional

An occupational therapist or physiotherapist can measure and fit a wheelchair, advise on cushions and posture and train the user and carer. This is particularly important for people at risk of pressure sores or with posture problems. Ask a doctor about any skin changes, pain or numbness. Our care advisors can arrange an assessment and plan equipment.

Measuring checklist

• Firm chair, normal clothes, shoes on.
• Hip or thigh width + about 5 cm.
• Buttock to back of knee − about 2.5 to 5 cm.
• Back of knee to floor + about 5 cm + cushion.
• Back of knee to sole of foot.
• Seat to bottom of shoulder blade.
• Seat to elbow + about 2.5 cm.
• Weight and door widths.