Wheelchair Seating Calculator

This calculator derives basic wheelchair seating dimensions -- seat width, seat depth, seat height above the footplate, seat-to-floor height, backrest height, and armrest height -- from four body measurements taken while the user is seated: hip width, thigh length, lower leg length, and trunk height, plus a Back Support Level selection. Each dimension follows a standard clinical seating rule of thumb: Seat Width adds a small fixed clearance to the measured hip width (about 3 cm here, at the low end of the 1-2 inch (2.5-5 cm) total clearance clinical seating guides recommend) so the user isn't pinched between armrests; Seat Depth subtracts about 4 cm from thigh length to keep the front edge of the cushion clear of the popliteal fossa (back of the knee), avoiding pressure on that sensitive area; Seat Height Above Footplate adds a fixed cushion-thickness allowance to lower leg length, and Seat-to-Floor Height adds a further 5 cm of footplate ground clearance on top of that -- a footplate set flush with the floor catches on every threshold and ramp transition, so 1 to 2 inches of clearance is standard; and Backrest Height and Armrest Height scale off Trunk Height, with Backrest Height driven by the selected Back Support Level (roughly two-thirds of trunk height for an active user up to the full trunk height for someone needing maximum support) and Armrest Height held at a fixed 45% of trunk height, tracking how seated elbow height runs roughly 40-45% of seated shoulder height rather than a single ~25 cm figure. Hip Width is the input the calculator responds to most, since it drives Seat Width directly and Seat Width is the primary highlighted output; the other three measurements each drive exactly one dimension and do not affect Seat Width at all.

Cushion selection is deliberately not calculated here: pressure-redistribution cushions are chosen on pressure-injury risk -- sensation, skin history, sitting tolerance, ability to perform pressure reliefs, and postural asymmetry -- not on body weight, and that assessment belongs to a seating clinician, not a formula. These are planning-stage clinical estimates from established rule-of-thumb ranges (referencing ISO 7176-7 measurement conventions and RESNA seating vocabulary), not a prescription: a certified Assistive Technology Professional (ATP) or seating clinician should confirm the final fit before ordering equipment.