Sihoo sells enough office chairs that the model names can become more confusing than the features. The useful way to narrow the range is to start with four questions: how much you want to spend, whether the published seat dimensions fit you, which adjustments you will use, and how much uncertainty you can accept when buying online.
How we researched this guide: Desworthy has not physically tested these chairs. We compared Sihoo’s current U.S. product pages, published dimensions, adjustment descriptions, availability, warranty, and return policy. Prices and stock were checked July 16, 2026. They can change without notice.
The short version
The M18 is the lowest-cost Sihoo chair in this guide and has unusually clear lumbar-adjustment details for its price. The M59AS is the more interesting space-saving option because its arms flip up and its published seat is shorter than the M18 or M57. The C300 Pro has the strongest balance of published seat, backrest, and arm adjustments without reaching Sihoo’s highest prices. The C300 Pro V2 adds more adjustment range, while the S300 is the premium recline-first model.
That does not make any one of them the universal winner. Sihoo often publishes overall chair dimensions or “max hip width” without a complete seat-height range. A capacity rating also says nothing about whether the seat is wide or deep enough for a particular person.
| Model | Price checked July 16, 2026 | Most useful published feature | Main caution |
|---|---|---|---|
| Sihoo M18 | $169.99 | Lumbar height and depth adjustment | Fixed 17.91-inch seat depth may be long for some users |
| Sihoo B100 | $219.99 | Flip-up arms and optional footrest configuration | U.S. page does not publish a complete seat-size range |
| Sihoo M57 | $239.99 | Full mesh, manual lumbar, and 3D arms | 18.11-inch fixed seat depth needs careful measurement |
| Sihoo M59AS | $239.99 | 3D flip-up arms and a 17.13-inch published seat depth | Narrower published “max hip width” is not a comfort guarantee |
| Sihoo B100 Pro | $259.99 | 4D flip-up arms and upgraded headrest adjustment | Official U.S. page omits important seat dimensions |
| Sihoo C300 | $279.99 | Flexible back, self-adaptive lumbar, and linked 4D arms | Seat-depth adjustability is unclear across Sihoo’s own pages |
| Sihoo C300 Pro | $359.99 | Adjustable seat depth, backrest height, and 6D linked arms | Costs substantially more than the M-series chairs |
| Sihoo C300 Pro V2 | $429.99 | Wider seat-depth range and 8D arm adjustment | Stock and selected-variant availability can differ |
| Sihoo S300 | $599.99 | Free-floating recline and extensive back and arm adjustment | Sihoo publishes conflicting 300-pound and 330-pound limits |
Choose the M18 when price comes first
The M18 is the easiest starting point for a buyer trying to stay below $200. Its official page describes manual lumbar adjustment in both height and depth, height-adjustable arms, a pivoting and height-adjustable headrest, tilt tension, and recline up to 126 degrees. Sihoo publishes a 17.91-inch seat depth and a 330-pound capacity.
The limitation is geometry. A deeper fixed seat can press into the back of the knees when a user’s thighs are shorter. Sihoo’s U.S. page does not provide enough seat-height detail to promise that the M18 will fit a particular height range. Measure first, and keep the packaging until you know the chair works with your body and desk.
Look at the M59AS or B100 family for a small workspace
The M59AS has a 17.13-inch published seat depth and arms that flip up, so it is easier to consider for a compact desk than the deeper M18 or M57. It also has a full mesh seat, dynamic lumbar support, and 3D arm adjustment. Sihoo lists a 19.88-inch “max hip width.” Treat that as a screening measurement, not proof of comfort.
The B100 and B100 Pro also have flip-up arms and three recline positions up to 135 degrees. The standard B100 is cheaper. The Pro adds a more adjustable headrest, 4D arms, and a different lower-back support system. The problem is missing data: the current U.S. pages do not publish the complete seat dimensions needed for a confident fit comparison. Ask Sihoo for those measurements before ordering if space or body fit is tight.
Choose the M57 for a simpler full-mesh chair
The M57 sits near the M59AS in price but follows a more conventional layout. It has a full mesh seat and back, manual lumbar adjustment, 3D arms, and recline up to 126 degrees. The official page publishes an 18.11-inch fixed seat depth and a 20.08-inch “max hip width.”
That deeper seat is the main reason not to buy it from a feature list alone. The M57 makes more sense for someone whose measurements work with the fixed seat and who prefers direct manual lumbar positioning over a more complex adaptive back.
The basic C300 is attractive, but one specification needs clarification
The C300 brings Sihoo’s flexible Doro back design below $300 at the checked price. Its official page describes self-adaptive lumbar support, a flexible backrest, linked 4D arms, and recline to 130 degrees. It publishes a seat-depth figure of 17.13 to 18.11 inches.
The range looks like an adjustment specification, but Sihoo’s own buying guide identifies the C300 Pro, S300, and S100 as the models with adjustable seat depth. Until Sihoo confirms the basic C300 mechanism, we would not buy it on the assumption that the user can slide the seat. Buyers who need depth adjustment should move to a model where that control is stated clearly.
The C300 Pro has the most balanced published adjustment set
The C300 Pro is the first model in the current range where the fit case becomes easier to document. Sihoo publishes an adjustable seat depth of 16.81 to 17.76 inches, backrest-height adjustment, 6D linked arms, a 20.28-inch “max hip width,” and a stated user-height range of 5 feet to 6 feet 3 inches.
Those numbers do not prove comfort, but they give an online buyer more ways to correct a borderline fit. The C300 Pro is the most defensible upgrade for someone who wants a Sihoo chair with adjustable seat geometry and does not need the extra controls or higher price of the V2.
The C300 Pro V2 is for buyers who will use the extra adjustment
The C300 Pro V2 expands the published seat-depth range to 16.9 to 18.5 inches and adds 8D arms, a larger 3D headrest, and a sacral-lumbar support design. Sihoo states a user-height range of 150 to 190 centimeters, roughly 4 feet 11 inches to 6 feet 3 inches.
More adjustments can improve the odds of finding a workable setup, but only if the controls cover the user’s measurements and remain easy to use. The V2 costs about $70 more than the C300 Pro at the checked prices. Compare the exact selected color, frame, and footrest option because stock and price can change by variant.
The S300 is a recline-first premium option
The S300 centers its design on a free-floating recline, dual dynamic lumbar support, 6D arms, upper-back adjustment, and adjustable seat depth. Sihoo publishes an approximate height range of 150 to 190 centimeters.
It is also the hardest model to recommend from specifications alone. Recline feel, mesh pressure, lumbar firmness, arm movement, noise, and long-term durability need hands-on evaluation. Sihoo’s page also conflicts on whether the capacity is 300 or 330 pounds. Buyers near either limit should obtain written confirmation before ordering.
What about the M56C and S100?
The M56C and S100 had live product pages when we checked, but both were sold out. The S100 was also absent from Sihoo’s current U.S. navigation. They may return, but a buying guide should not steer a reader toward an unavailable chair when close substitutes are in stock.
Sihoo’s warranty and return policy need a careful reading
Sihoo states a three-year limited warranty for manufacturing, structural, and mechanical defects under normal use. The warranty is limited to the original purchaser and excludes normal wear, misuse, and modifications.
The central return page states a 30-day window and describes return shipping as free in the United States and Canada. The same page contains conflicting condition language. One section says the product must be unused and in original packaging, while a later FAQ allows normal use and returns for discomfort or fit. Keep the box and packing materials, photograph the chair’s condition, and ask support to confirm the return conditions in writing before the deadline.
How to make the final choice
- Measure the floor-to-knee height, thigh length, seated hip width, and the clear space under the desk.
- Remove models whose published seat dimensions do not fit those measurements.
- Decide whether fixed geometry is acceptable or whether you need adjustable seat depth and back height.
- Compare the exact return conditions as well as the advertised trial period.
- Check the product page again on the day you order. Sihoo’s prices, variants, and availability move often.
If you are still deciding between brands, read our under-$300 chair guide. For help checking your measurements, use our online ergonomic chair fit guide.
Sources
- Sihoo U.S. office-chair collection
- Sihoo return policy
- Sihoo warranty policy
- Individual official product pages linked in the comparison table above