A properly adjusted ergonomic chair puts your feet flat, hips and knees near 90°, and your lumbar cushion in the small of your back.
A chair two inches off can leave your feet dangling, press the seat edge into your knees, and push your shoulders up — all before lunch. Five adjustments fix most of it, each in under a minute. Here’s the order, what “right” feels like, and the mistakes that undo it.
What Order Should You Adjust the Chair In?
Work bottom-up: seat height, seat depth, backrest and lumbar support, then armrests. Changing height after setting armrests means redoing the armrests, since everything above the seat shifts when the seat moves. The Canadian Centre for Occupational Health and Safety’s chair adjustment guidance uses this sequence, as do university ergonomics teams.
Order matters because your hips, knees, and elbows reference each other — set the height wrong and the armrest height will be off by the same amount.
How Do You Set Seat Height and Seat Depth?
Set height so feet rest flat, thighs sit parallel to the floor, and knees are level with or slightly below your hips. Shortcut: stand beside the chair, bring the seat to knee height, then sit and check.
For depth, leave about two inches — or two to three finger widths — between the seat’s front edge and the back of your knees to avoid pressure and slowed circulation.
If your desk is fixed and the correct height leaves feet floating, add a footrest; raising the chair until feet dangle trades one problem for a worse one.
How Should the Backrest and Armrests Be Set?
Fit the lumbar cushion into the small of your back, then set a slight recline — commonly 90 to 110 degrees of hip angle — supporting your lower back’s natural inward curve. Armrests come last: set them so elbows sit around 90 degrees with shoulders dropped. They should lightly carry your forearms, not prop your shoulders up. If they won’t go low enough or block you from pulling close to the desk, removing them is a legitimate fix — more than one ergonomics guide says so outright.
Once set, sit a few minutes and make small changes until the posture feels neutral and sustainable. Only a chair with enough adjustment range to fit your body counts as ergonomic.
| Adjustment | What “Right” Feels Like | Common Mistake |
|---|---|---|
| Seat height | Feet flat, thighs level, knees at or just below hip level | Chair too high, feet dangling |
| Seat depth | About 2 inches of clearance behind the knees | Seat edge pressing the calves |
| Lumbar support | Cushion in the small of your back, slight recline | Support too high, too low, or too forceful |
| Armrest height | Elbows near 90°, shoulders dropped | Armrests so high they lift the shoulders |
| Armrest width | Forearms supported without reaching | Set too far out to give any support |
| Backrest angle | Neutral curve held, no pressure points | Locking fully upright all day |
| Foot support | Footrest under the feet when the desk is fixed high | Raising the chair instead of adding a footrest |
Some chairs use a ratchet-style backrest height mechanism that must be raised to its top position before it drops. If yours won’t lower, that’s usually why — not a broken chair.
If your chair can’t reach these settings, the limits are in the chair. Our tested roundup of chairs built for long sitting sessions covers which models adjust far enough for a full workday.
Finally: chair adjustment fixes posture, not sitting itself. Long stretches in any chair remain a risk factor, and both the CCOHS guidance and Haworth’s ergonomic seating guide point to movement breaks and task changes. Adjust the chair, then get up now and then.
Sources
- Canadian Centre for Occupational Health and Safety. “Office Ergonomics — Chair Adjustment.” Source for the seat height, depth, backrest, and armrest adjustment sequence.
- Haworth. “Ergonomic Seating Guide.” Supports hip angle range, lumbar fit, and the need for movement breaks.
- UC Davis Safety Services. “Office Computer Ergonomics — Chair.” Supports armrest removal when they cannot be adjusted low enough.
Common Questions
How do I know if my chair is too high?
If your feet don’t rest flat on the floor, it’s too high. Dangling feet pull your thighs down and tilt your hips, throwing off every setting above the seat. Lower the seat until feet sit flat and thighs are roughly parallel to the floor, or add a footrest if desk height won’t allow it.
Should the lumbar support touch my back all the time?
Yes, but lightly. The cushion should sit in the small of your back and follow its natural inward curve without pushing you forward. Set too high, it lands on your mid-back and does nothing useful; too low or too forceful, it creates pressure instead of relief. Move it until it feels like a gentle fill, not a shove.
Can I remove the armrests on my office chair?
Often, yes. Guidance recommends removing armrests when they can’t be set low enough for relaxed shoulders, or when they stop you sitting close to the desk. Many chairs unbolt with a basic screwdriver. Check your assembly instructions first and keep the hardware in case you want them back.