SIHOO M18 Ergonomic Office Chair: problems, parts and running costs

Checked: 2026-10-05

Summary

The SIHOO M18 is a budget ergonomic chair with a padded sponge seat, mesh back, headrest and lumbar that adjusts vertically and in and out, and it is rated for 330 lb. The seat and recline are well liked, but the lumbar pad is the most consistent complaint, described as hard or intrusive, and some owners remove it; the arms are height-only and the seat depth is fixed at 17.91 in. There are no consumables or electrical parts, so running cost is only occasional wear parts, and it is strong value at $140 or less and conditional above about $180.

Common problems and fixes

Hard or intrusive lumbar pad — the most consistent owner complaint across multiple threads, and some owners remove the pad entirely, while professional testers liked it after adjustment. This is a genuine fit disagreement, so check it before the return window closes. [3][8][9]
Armrests are height-only despite the 2D label — no width or fore/aft adjustment was established, and armrests recur as hard or awkward. [3][10]
Fixed seat depth — the 17.91 in seat cannot be extended, which limits fit for some body types. [1][3]
Stock casters collect hair and dirt — they can roll poorly or resist changing direction, so clean the axles. [3][4]
Seat comfort is polarizing over long sessions — testers got about seven comfortable hours, while some owners report a hard or flattening feel and tailbone discomfort. [3][9]
Adjustments are stiff — TechGearLab found the controls stiff and scored adjustability low. [3]
Isolated mechanical problems — squeaking, loose armrest screws, weakening recline tension, torn arm pads and one weld failure after years are reported as signals, not a failure rate. Re-tighten the armrest bolts periodically. [5][6][10]
Assembly takes effort — TechGearLab put its unit together in 16 minutes but scored assembly low, and regional dimension listings conflict, so trust the US numbers. [1][3]

Parts and consumables

No replaceable parts or consumables reported — the chair is entirely mechanical with no electrical parts or filters. SIHOO favors mailing replacement parts for covered problems, but no comprehensive retail parts catalog or pricing was verified. [1][2]
Wear points — the stock casters and arm pads are the parts owners most often mention replacing or cleaning, and no official part numbers or prices were found. [3][4]

Yearly running cost

Not enough data for a figure. There are no consumables, no subscription and no electrical parts, so the only recurring cost is occasional cleaning and the wear parts above, none of which has a published price. [1][2]

When it is a good buy

SIHOO’s US store listed the M18 at $169.99 in September 2026 against a regular $289.99, a price tracker recorded the same $169.99 on 2026-09-09, and a marketplace snapshot put it near $132.53. [1] Bands: excellent at $140 or less; strong at $140 to $160; fair-to-good at $160 to $175; conditional above about $180, where the fixed seat depth and height-only arms argue for comparing more adjustable new chairs. [1][3] Named alternatives:

IKEA Marcus — the better choice when you want a simpler, more widely available chair and can give up the adjustable lumbar. [7]
A used or refurbished commercial chair — the better choice near $200 when adjustability and long-term support matter more than buying new. [3]