It is the budget chair that keeps appearing on serious shortlists, and the thing you most need to know about it is a number that is not on the spec sheet.
Picked on published fit specifications, not on hands-on testing. How we pick.
The short answer
The Doro C300 has the two adjustments that matter most over a long day - seat depth and a backrest that lifts - at a budget price with a 330-pound rating. The gap is that Sihoo publishes overall chair height and no seat height, which is the number that decides fit.
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The verdict
The best-specified budget chair we could find, with one significant caveat. It appears at or near the top of the under-$300 page, the sciatica page and the long-hours budget page for a single reason: it adjusts seat depth, and almost nothing else at the price does.
The caveat is that Sihoo publishes overall chair height of 42 to 49 inches and no seat height at all. For a purchase that lives or dies on whether the seat matches your legs, that is a real gap, and we would rather say so plainly than quote an overall height as if it were a seat height.
The published specifications
Sihoo Doro C300 published specifications
Specification
Published figure
What it means for you
Seat height
Not published
The single most important fit number, and it is missing
Overall height
42-49 in
Total chair height, not seat height - do not confuse the two
Seat depth
18.11 in, adjustable
Suits thigh lengths from roughly 5 ft 10 in up; the slider helps below that
Seat width (max hip)
20.28 in
Standard width
Backrest lift
18.11-21.65 in
3.5 in of travel - moves where the lumbar contact lands
Armrests
4D coordinated
Up, down, in, out, forward, back, with tilt linkage
This matters enough to give its own section. Sihoo publishes overall chair height - the distance from the floor to the top of the headrest - and not seat height. Those are completely different numbers and only one of them tells you whether your feet will reach the floor.
Three practical responses:
Work out your number anyway. Roughly a quarter of your standing height, from the seat height table. You need it regardless.
Measure the chair when it arrives and return it if the seat will not drop to your number. Buy from a seller with a returns window.
Budget for a footrest. Costs very little, solves the problem entirely, and removes the risk from the purchase.
Why the seat depth adjustment matters so much
The 18.11-inch pan is long. Against the seat depth estimate, an 18.11-inch pan suits a sitter of roughly 5 ft 10 in and up. Below that, a fixed 18.11-inch pan would press into the back of your thighs all day.
The slider is what makes the chair work for everyone else, and it is the reason we recommend it over the cheaper Sihoo M57, which publishes the same 18.11-inch pan and does not list a depth adjustment.
Where it is strong
Seat depth adjustment. The adjustment that matters most over a long day, and rare at this price.
3.5 inches of backrest lift. Functionally a form of lumbar adjustment - moving the whole back changes where support lands. Rarely described that way.
A genuine mesh seat. Mesh on both surfaces, not mesh over foam.
4D coordinated armrests. More directions than several chairs costing twice as much.
330-pound rating. Higher than the Branch Ergonomic Chair at a lower price.
Where it is weak
No published seat height. Covered above. The biggest issue.
Three-year warranty. A quarter of Steelcase's, and an honest signal about expected duty.
Self-adapting lumbar, not positionable. The backrest lift moves the contact point, but there is no pad you place and no firmness control.
Not a tensioned suspension seat. A genuine mesh seat, and not the same engineering as an Aeron. See best mesh office chairs.
No published armrest ranges. 4D is a count, not a measurement.
Who should not buy one
Anyone over 330 lb.
Anyone doing eight-hour days five days a week who expects the chair to last - the Series 1 costs more and is warrantied four times as long, multi-shift.
Anyone who needs to confirm fit before ordering, without a returns window.
Anyone with a specific, localized back pain needing a positionable lumbar pad.
Built on Sihoo's published figures, with the gaps stated rather than filled in. See how we pick.
The published specifications
Budget, with the adjustments that matter
Sihoo Doro C300
Most budget chairs give you a height lever and a tilt lock. This one publishes an 18.11-inch seat pan with depth adjustment and a backrest that lifts through 18.11 to 21.65 inches - which together mean you can set both where the pan ends and where the lumbar contact lands. Those are the two things that decide whether a chair is tolerable at hour seven. Add 4D coordinated armrests, a self-adapting lumbar, a 330-pound rating and a three-year warranty, and it is the best-specified budget chair in our registry.
Who it fits
Anyone of roughly average height on a real budget, especially anyone whose complaint is thigh pressure.
Who it does not fit
Anyone who needs a confirmed seat height before ordering - Sihoo does not publish one - and anyone over 330 lb.
It is the best budget option in our registry for thigh pressure and general desk ache, because it adjusts seat depth and lifts the whole backrest. For pain at a specific location you want a positionable lumbar pad, which it does not have.
What is the Doro C300 seat height?+
Sihoo does not publish one. The 42 to 49 inch figure on the spec sheet is overall chair height, which is a different measurement. Measure on arrival, or budget for a footrest.
Doro C300 or Sihoo M57?+
The C300 for the seat depth adjustment, the backrest lift and 4D armrests. The M57 is cheaper with the same 330-pound rating and three-year warranty, and no depth slider. If your thigh length comfortably suits an 18.11-inch pan, the M57 saves you money.
Is the Doro C300 real mesh?+
Sihoo publishes mesh on both the back and the seat, which is less common in the budget tier than listings suggest. It is not tensioned suspension in the Aeron sense - different engineering, different price.
