Office chairs ship with one type of caster, and it suits one type of floor. Most people have the other type.

Two Kinds of Caster

Hard casters, usually black nylon, are designed for carpet. They are firm so they roll over pile rather than sinking into it.

Soft casters, usually with a polyurethane tyre and often clear, are designed for hard floors. The softer material grips and cushions rather than skidding.

Most chairs ship with hard carpet casters, because they are cheaper.

What Happens When They Are Wrong

• Hard casters on wood or laminate scratch it, permanently
• They also roll too freely, so the chair drifts
• Soft casters on thick carpet drag and are hard work
• Grit trapped in any caster grinds into the floor beneath
• Neither is a fault; it is a mismatch

Where a listing states the caster type, of the kind noted per model at stellamia.org, that is worth checking against your actual floor before ordering.

Casters Are Easily Swapped

The fix nobody realises is available. Office chair casters are almost all a standard eleven millimetre stem, and they pull out and push in by hand.

A set of soft rollerblade-style casters costs very little and takes two minutes to fit. For anyone with a hard floor and a scratching chair, it is the single best small purchase available.

Some require a firm pull, and levering with a flat bar helps.

Chair Mats

The alternative, and they have drawbacks.

Hard mats on carpet can crack under a heavy chair, and their edges are a trip hazard. On hard floors they protect but slide, and cheap ones dent under casters.

Swapping the casters is generally the better solution on hard floors.

Underfloor Heating

Some flooring manufacturers advise against hard casters entirely over heated floors, and some against chair mats trapping heat.

Worth checking the flooring guidance rather than the chair’s.

Clean Them

Hair and grit wrap around caster axles and stop them turning, so they drag rather than roll. That is what scratches floors.

Turning the chair over twice a year and cutting the debris out takes five minutes.

Locking Casters Exist

They brake when the chair is unweighted, which suits sloped floors and anybody who finds a chair drifting.

Never Stand on the Chair

Casters and standing are the classic combination behind serious falls.