Office chairs

Do Seat Cushions and Lumbar Pillows Fix an Office Chair, or Make It Worse?

Published October 31, 2026 · By Ergocrew · Specs and guidance as of that date, from the pages under Sources

What a cushion changes in the chair's geometry

The chair's mechanisms stay in place when you add a cushion. Your body moves relative to them in two ways.

• Height: a cushion raises the sitting surface by its compressed thickness, which depends on the cushion and load. ProtoArc lists both SC Butterfly models as 4.3 in thick. That listing dimension is not a measured increase in occupied seat height, so do not simply add 4.3 in to the chair's setting.
• Depth: a cushion with a raised or thick back edge, or a lumbar pillow behind you, takes up room between your hips and the backrest. You end up sitting further forward, which works like a seat that is shallower than before.

The backrest stays where it was. Raising your hips relative to the backrest changes which part of your back meets the backrest's curve. Our guide to lumbar support covers where that curve belongs.

When a cushion or pillow can help

CCOHS, Canada's occupational health agency, states the aim of a workstation this way: it "should let the worker sit and carry out their duties in comfort while allowing for voluntary changes in the working position." A cushion fits that aim where the chair cannot reach your setup by its own adjustments.

• The seat will not go high enough. At a fixed-height desk, CCOHS sets chair height so your elbows are about level with the work surface, at about 90 degrees. If the chair tops out below that, a cushion adds height the gas cylinder cannot.
• The seat is too deep. If you cannot sit back without the front edge pressing behind your knees, CCOHS's check is a gap of about 2 inches, roughly a clenched fist, between the seat edge and your calves. A lumbar pillow that moves you forward can create that gap on a chair with no depth adjustment.
• The seat surface itself is hard and the height already has room to come down. Readjust the chair while seated on the cushion; its compressed thickness determines the height change.

When it makes the fit worse

The trouble starts when the chair already fit. CCOHS's sitting guidance says "The basic requirements are to have a workstation and job tasks designed to allow a person to remain in a neutral posture," and it describes the soles of the feet at 90 degrees to the lower legs. Adding a cushion without readjusting a correctly set chair can leave your feet short of the floor.

• If the chair is at its lowest setting and you add a cushion, you cannot lower it to compensate. OSHA's chair guidance says to use a footrest when the seat cannot be lowered, and CCOHS asks for an adjustable footrest that supports both feet flat.
• Your elbows rise relative to the desk. A keyboard that sat at elbow height is now below it.
• A seat that was the right depth becomes too shallow when a pillow or a thick cushion edge pushes you forward, leaving less of your thighs supported.
• Armrests set for your old height may now sit too low. OSHA asks for armrests "low enough for relaxed shoulders" and close enough to support the lower arms, which depends on where you sit.

ProtoArc's cushions and their sizes

Dimensions are as ProtoArc lists them; prices are at ProtoArc's US store, checked 2026-10-13.

The XL is 16.9 - 15.7 = 1.2 in wider and 20 - 18.3 = 1.7 in deeper, for $49.99 - $32.99 = $17 more at ProtoArc's US store, checked 2026-10-13. ProtoArc lists memory foam and a cotton cover on both, and describes the XL foam as CertiPUR-US certified. Their equal listed thickness does not establish an equal rise under load.

If your seat can accommodate a 15.7 x 18.3 in cushion and you can readjust around it, the standard SC Butterfly at $32.99 on that date is the smaller option to examine. Compare its full footprint with your seat and confirm dimensions and returns with ProtoArc; seat depth alone does not establish fit.

The separate Chair Seat Cushion Bundle is configurable, so compare its selected contents and checkout total rather than treating it as another single cushion.

Re-adjusting the chair after adding one

Sit on the cushion before making the final adjustments. An empty cushion's dimensions will not tell you where your elbows and feet end up; our guide to chair adjustments explains the wider setup sequence.

• Height first: sit on the cushion and lower the chair until your elbows are about level with the desk. If the chair is already at its lowest, add a footrest or reconsider the cushion.
• Feet: check that the soles rest flat, at about a right angle to the lower legs.
• Depth: sit all the way back and check the fist-width gap behind your knees. OSHA's guidance calls for a depth-adjustable seat, so use that adjustment before reaching for a pillow.
• Backrest: OSHA lists lumbar support as height adjustable. If your chair has that adjustment, reset it after the cushion raises you, rather than stacking a pillow on top of it.
• Armrests and desk: reset the pads to support your forearms without pushing your shoulders up, then check the keyboard against your elbows. The required direction depends on the chair height after adjustment.

If the chair already meets those fit checks, identify what you want the cushion to change before adding it. A preference for a different seat surface still needs a fit check afterward.

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