Picked on published fit specifications, not on hands-on testing. How we pick.
The short answer
The M57 keeps the things that cost little - a mesh seat, a 330-pound rating, a three-year warranty - and gives up the things that cost more: a seat depth slider, 4D armrests and a backrest that lifts. For a sitter whose thighs suit an 18.11-inch pan, that is a reasonable trade.
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The verdict
Good value for a specific body type, and the wrong purchase for a lot of people who will be told it is good value. The deciding number is seat depth: Sihoo publishes an 18.11-inch pan and does not list a depth slider, so if your thigh is shorter than that, the front edge will press behind your knees and there is nothing you can do about it.
On the seat depth estimate, an 18.11-inch pan suits a sitter of roughly 5 ft 10 in and up. Below that, spend the extra on the Doro C300, which publishes the same pan with a slider.
The published specifications
Sihoo M57 published specifications
Specification
Published figure
What it means for you
Seat height
Not published
The most important fit number, and it is missing
Overall height
42-49 in
Total chair height, not seat height
Seat depth
18.11 in
No slider listed - this is what you get
Seat width (max hip)
20.08 in
Standard
Armrests
3D
Up, down, left, right, forward, back - no tilt linkage
The first two rows are the whole difference, and they are the two adjustments that most affect how a chair feels at hour seven. Whether the gap is worth the price difference depends entirely on your thigh length: if 18.11 inches fits you, it is not.
Where it is strong
330-pound rating. Higher than the Branch Ergonomic Chair, at a fraction of the price.
A genuine mesh seat. Sihoo describes a PE polyester mesh, which puts it in the breathable category rather than the mesh-look category.
Three-year warranty. Longer than a lot of chairs at this price.
An enormous upgrade from a dining chair. Which is the realistic comparison for most people buying at this price, and worth saying plainly.
Where it is weak
No seat depth adjustment listed. The biggest limitation, and it decides who the chair suits.
No published seat height. Overall height only, as with every Sihoo chair here.
3D armrests, not 4D. Minor.
No backrest height adjustment published. So the lumbar contact lands where the mold put it.
Three-year warranty against twelve. For eight-hour days, five days a week, that difference is the whole argument for spending more.
What Sihoo publishes, and what it does not
Worth spelling out, because it is the pattern across the whole budget tier and the M57 is a clean example of it.
Published: overall chair height (42 to 49 inches), seat depth (18.11 inches), maximum hip width (20.08 inches), armrest directions (3D), weight capacity (330 pounds), warranty (three years), and the seat material (PE polyester mesh).
Not published: seat height from the floor, seat depth adjustment range if any, armrest height range, armrest width range, backrest height adjustment, and lumbar adjustment range.
Read that list again and notice what is on each side. The published figures are the ones that make a chair sound capable - a high weight rating, a generous seat depth, a mesh seat. The unpublished ones are the ones that decide whether it fits you. That is not unique to Sihoo; Hbada does the same, and so does most of the tier.
The practical response is the one we give on every budget page: work out your own numbers from the seat height table, buy from a seller with a real returns window, measure the chair when it arrives, and send it back if the seat does not drop to your figure. That turns a missing specification from a risk into an inconvenience.
Living with one
If you buy this chair, two small additions do more for it than anything in the next price band would:
A footrest if the seat will not drop to your number. It produces the same joint angles as a lower chair and costs a fraction of one.
A strapped lumbar cushion placed at the point where your back actually curves. The M57's lumbar support is not positionable, so a cushion gives you the one control the chair does not have. See best lumbar support cushions.
Together those two cost less than the gap between this chair and the Doro C300, and they address different things - so if your issue is seat height or lumbar placement rather than pan length, this combination is the cheaper correct answer.
Who should not buy one
Anyone under about 5 ft 8 in. The fixed 18.11-inch pan is likely longer than your thigh and cannot be shortened. Buy the Doro C300 instead.
Anyone over 330 lb.
Anyone doing genuine full-time desk work who wants a chair that lasts.
Built on Sihoo's published figures, with the gaps stated rather than estimated. See how we pick.
The published specifications
The most rating per dollar
Sihoo M57
Sihoo publishes an 18.11-inch seat depth, a 20.08-inch maximum hip width, a 330-pound capacity and a three-year warranty, with a PE polyester mesh seat and 3D armrests. For someone currently working from a dining chair, that is a large upgrade for a small amount of money, and the 330-pound rating is higher than chairs costing three times as much. What it does not have is the Doro C300's seat depth slider or backrest lift.
Who it fits
Sitters of roughly 5 ft 10 in and up, whose thigh length comfortably suits an 18.11 in pan.
Who it does not fit
Anyone under about 5 ft 8 in, whose maximum seat depth is shorter than 18.11 in with no slider to correct it. Anyone over 330 lb.
For a sitter of roughly 5 ft 10 in and up, on a tight budget, yes - a 330-pound rating and a genuine mesh seat at this price is good value. For anyone shorter, the fixed 18.11-inch seat pan is the problem and the Doro C300 is the better buy.
What is the Sihoo M57 weight limit?+
330 pounds, per Sihoo's published specification table.
Does the M57 have adjustable seat depth?+
Sihoo does not list one. The published seat depth is 18.11 inches, and that is what you get. The Doro C300 publishes the same pan with adjustment.
Is the M57 good for long hours?+
For a few hours a day, yes. For eight hours five days a week, the three-year warranty is Sihoo telling you what they expect - and a Steelcase Series 1 is warrantied twelve years multi-shift for a reason.
