The chair adjustments that actually matter
Task chairs advertise a long list of adjustments. Four of them change how you feel at hour six; the rest are mostly there to lengthen the list.
Chair listings compete on the number of adjustments. Some of those adjustments address real problems that real bodies have. Others exist because a longer specification list looks better than a shorter one.
Knowing which is which changes what you should be willing to pay for.
The four that matter
Seat height
The foundational one, and the only adjustment essentially every chair has.
Set it so your feet rest flat on the floor with your thighs roughly parallel to it. Too high and your feet dangle, putting pressure on the underside of your thighs. Too low and your knees rise above your hips, which rotates your pelvis back and rounds your lower spine — the position that produces lower-back complaints.
If your desk is fixed at a height that forces your chair too high for your legs, a footrest is the correct fix. Not raising the chair less.
Seat depth
Frequently absent on cheaper chairs, and the one whose absence people feel without identifying.
You want two to three finger widths of gap between the front edge of the seat and the back of your knees. Too deep and the seat edge presses into your calves, so you slide forward to escape it and lose contact with the backrest — which is how you end up perched on the front third of an expensive chair, unsupported. Too shallow and your thighs are unsupported.
Bodies differ substantially in leg length at the same overall height. A seat depth that fits one person will be wrong for another.
Lumbar support position
Not merely whether it exists — whether it moves.
Your lower back has an inward curve, and support belongs at the deepest point of it. That point sits at a different height on different people. A fixed lumbar bulge is placed for an average; if your average differs, it pushes on the wrong vertebra all day, which is worse than no support.
Height-adjustable lumbar is the meaningful version. Depth adjustment on top of that is a refinement.
Armrest height
Your shoulders should be relaxed with your elbows at roughly ninety degrees.
Armrests too high push your shoulders up towards your ears — you will not notice at first and will notice by the afternoon. Too low and you either lean to reach them or stop using them, at which point your arms hang from your shoulders all day.
Height is the adjustment that matters. Width and pivot are conveniences.
The ones that matter less than the listing suggests
Recline tension. Useful, but a fixed tension appropriate to your weight is fine. This is a comfort refinement, not a health one.
Headrest. Only does something if you actually recline. Sitting upright at a desk, your head is balanced over your spine and touching nothing. Many people buy the headrest version and never contact it.
4D armrests. Height is what matters. Depth and pivot get used briefly and then stay wherever they were left.
Seat tilt. A genuine ergonomic tool for specific needs, but for most desk work the flat position is the one that gets used.
Mesh versus foam. A materials preference, not an ergonomics tier. Mesh breathes better; good foam distributes pressure better; bad versions of either are bad. This is comfort, and comfort is worth caring about — it is just not the same axis as adjustment.
What warranty tells you
Chair mechanisms fail before chair fabric does. Gas cylinders sink, tilt mechanisms develop play, armrest posts loosen.
A twelve-year warranty is a manufacturer betting real money that theirs will not. A one-year warranty is the legal minimum in many places and tells you nothing. This is the closest thing to a durability signal a specification sheet offers, and it is on every listing on this site for that reason.
Check what the warranty covers. Some cover the frame for a decade and the mechanism for two years, which is the part that breaks.
How to evaluate a chair you cannot sit in
Buying online means you cannot test it, so read the specification for the four adjustments above:
- Seat height — what is the actual range in centimetres? Not “adjustable.”
- Seat depth — is it adjustable at all? Many chairs simply are not.
- Lumbar — is it height-adjustable, or a fixed shape?
- Armrests — height-adjustable at minimum?
A chair with all four, in plain materials, will serve you better than a chair with an impressive headrest, elaborate mesh, and a fixed seat pan.
Then check the return policy, because bodies are individual and the specification only gets you close.