How to Adjust a Used Ergonomic Office Chair: Lumbar, Seat Depth & Arms Explained

Buying a used ergonomic office chair is only half the win. The other half is adjusting it properly. A Herman Miller Aeron or Steelcase Leap set up wrong will still leave you sore by 3 p.m., while a mid-priced chair dialled in to your body can feel supportive all day. Most premium used chairs share the same core adjustments, and you can set them in about five minutes.

Start with seat height and seat depth

Sit in the chair with your feet flat on the floor and set the height first. Use the paddle or lever under the right side of the seat — on most Steelcase, Haworth, and Knoll chairs it is the front lever. Your knees should sit at roughly 90 degrees, thighs parallel to the floor, with no pressure under the back of your thighs. If your feet dangle, the chair is too high. If your knees are above your hips, it is too low.

Next, check seat depth. You want two to three fingers of space between the front edge of the seat and the back of your calves. On a Steelcase Leap V2, slide the seat forward or back with the side lever. On a Herman Miller Aeron, depth is fixed by size — Size A, B, or C — which is exactly why sizing matters when you buy used: a Size C Aeron will never fit a smaller frame, no matter how you adjust it. If the seat edge presses into your calves, circulation suffers and your legs will go numb on long days.

Set lumbar support where your back actually curves

Lumbar support should meet the natural inward curve of your lower back, just above your belt line — not in the middle of your back and not pushing into your tailbone. Most buyers set it too high and too firm, then decide the chair is uncomfortable.

On the Steelcase Leap, two controls do this job: a height dial on the back that slides the lumbar pad up or down, and a firmness dial on the side. Start soft, slide the pad until it fills the curve of your spine, then add firmness gradually over a few days. On an Aeron with PostureFit, the knob tightens support across the sacrum and lower back — PostureFit models run about $750 CAD used versus $700 CAD for basic lumbar, and that $50 CAD difference is the feature owners feel most. On Haworth Zody and Fern chairs, the lumbar is asymmetrical and height-adjustable, designed to follow you as you shift. The test is simple: sit back fully, and you should feel even contact along your whole back with no gap at the waist.

Adjust the arms so your shoulders can drop

Armrests exist to take weight off your neck and shoulders — but only at the right height. Set them so your elbows rest lightly with your shoulders completely relaxed, forearms roughly parallel to your desk. If the arms are too high, they shrug your shoulders toward your ears. Too low, and you lean sideways to reach them.

Premium used chairs add width, depth, and pivot adjustments — the 4-way arms on a Leap V2 or a Knoll ReGeneration are a big reason those chairs command $249 to $600 CAD used instead of sitting in the $100 CAD entry band. Slide the pads in or out so your arms hang straight from your shoulders, and pivot them slightly inward if you type for long stretches. Working at a desk in the GTA? Bring the chair to desk height and check that the arms clear the desktop or slide just under it before you commit to a set of 20 for the office.

Dial in tilt tension and back angle

Recline is not slouching — a slight recline of 100 to 110 degrees takes pressure off your spinal discs. Unlock the tilt, lean back, and adjust the tension knob (usually the large dial under the front of the seat) until the chair supports your weight without pushing you forward or letting you fall back. Heavier users need more tension; lighter users need less, and a chair that feels broken is often just set for someone else's weight.

Then set your tilt limiter if your chair has one — free recline for calls, a more upright lock for keyboard work. Test every lever before you buy used: tilt should move smoothly, lock where you leave it, and the cylinder should hold your height without sinking. At Ufficio Furniture, every used chair is tested for exactly this before it goes on the floor.

Shop used ergonomic chairs in Mississauga and try the adjustments yourself

No guide replaces sitting in the chair. Ufficio Furniture stocks used ergonomic chairs from Herman Miller, Steelcase, Haworth, and Knoll — from $100 CAD for solid entry task chairs to $600 CAD for a Leap V2 and $700–$800 CAD for a fully loaded Aeron, against $1,600–$2,400 CAD new. Browse current stock at https://www.ufficiofurniture.com/seating , visit us at 1215 Meyerside Drive, Unit 7, Mississauga ON, or call 647-898-8918 and we will talk you through which model fits your body and budget. We are open Monday to Saturday 10am–7pm and Sunday 11am–6pm. Come in, sit down, and adjust three or four chairs side by side — your back will tell you which one is right.