Desworthy Editorial Team
Desworthy editorial reviewer focused on ergonomic chair research, desk tech, affiliate disclosure, and practical UK home office buying decisions.
Last reviewed on by Desworthy Editorial Team.
Choose the model, then check the current offer
Use the fit guide, budget shortlist, and Sihoo comparison together. When you know the right lane, move to the live chair deal feed.
Short answer: choose the Sihoo M18 when you need more published adjustment at a budget price, the Sihoo Doro C300 when you value its flexible-back and coordinated-arm design, or the IKEA MARKUS when a simple high-back chair with a documented 10-year guarantee matters more than extra controls. The right choice depends on your measurements and desk, not on which chair happens to have the largest sale badge today.
How we researched this guide: Desworthy has not physically tested these chairs. We use manufacturer pages for specifications and warranty facts, UK retailer pages for dated buying information, and named external reviews only as external evidence. We checked the linked sources on 3 August 2026. Prices, sellers, variants, delivery, and returns can change before checkout.
Quick answers about ergonomic chairs under £300
What is the best ergonomic chair under £300?
It depends on the problem you need the chair to solve. The Sihoo M18 is the budget-led adjustment option in this comparison, the Doro C300 is the feature-led option when the exact standard version stays within budget, and the IKEA MARKUS is the simpler high-back choice with a long published guarantee.
What should I measure before ordering?
Record your floor-to-knee height, thigh length, seated hip width, seat-to-elbow height, and the clear space beneath the desk. Compare those measurements with the seat-height range, usable seat depth and width, and the lowest armrest position for the exact model.
Does “under £300” include the real cost?
Not always. Check the selected colour or configuration, delivery charge, return shipping, and any assembly or collection cost. A chair that costs slightly less at checkout can be the riskier purchase when the return route is unclear.
How these three chairs compare
| Chair | Why it is in this comparison | Fit and adjustment trade-off | Buying context |
|---|---|---|---|
| Sihoo M18 | Budget option with published lumbar height and depth adjustment, armrest height adjustment, and a headrest. | Fixed 17.91-inch seat depth. Sihoo does not publish a complete UK seat-height range. | Sihoo UK showed £149.99 when checked. Compare the exact variant and retailer terms before paying. |
| Sihoo Doro C300 | Feature-led upgrade with a flexible back, self-adaptive lumbar design, coordinated arms, and a weight-sensing recline mechanism. | Do not assume the stated seat-depth figures mean a seat slider. The standard model needs confirmation if adjustable depth is essential. | Black / Standard showed £259.99 when checked. Footrest versions cost more, so compare the selected configuration. |
| IKEA MARKUS | Established simple high-back choice with a stated 10-year guarantee and a large public owner-review count on IKEA UK. | Its geometry and armrests are less adjustable than the Sihoo options. Check seat height and fixed lumbar position first. | IKEA UK showed £159 when checked, plus a stated 365-day full-refund return window subject to its conditions. |
These are comparison roles, not a claim that one chair fits everyone. A temporary sale can make a chair more attractive today, but it does not change its seat geometry, controls, warranty, or suitability for your desk.
Sihoo M18: the budget adjustment pick
The M18 is the best starting point here if you want to compare a fixed-seat budget chair with more published adjustment than a basic task chair. Sihoo lists lumbar adjustment in height and depth, height-adjustable arms, a pivoting and height-adjustable headrest, tilt tension, and recline up to 126 degrees.
Its main limitation is fit certainty. The stated 17.91-inch seat depth cannot be shortened, and the UK page does not publish a full seat-height range. Measure your thigh length and floor-to-knee height before you order. A fixed seat can work well when it already fits, but it gives you less room to correct a borderline fit.
Independent reference: Creative Bloq published a hands-on M18 review covering comfort, ergonomics, assembly, materials, and price. That is the reviewer’s experience, not a Desworthy test, and it should not override your own fit check.
Consider it if: you want adjustable lumbar positioning at the budget end and the published seat depth works for you.
Skip it if: you need a verified adjustable seat pan, a published low minimum seat height, or a retailer with a return route you have not yet checked.
Sihoo Doro C300: the feature-led upgrade
The C300 is the stronger comparison for someone who values a back that moves with them and armrests designed to coordinate with reclining posture. Sihoo describes a flexible backrest, self-adaptive lumbar support, a wide headrest, coordinated arms, and a weight-sensing recline mechanism. Those features make it more relevant than the M18 for buyers prioritising movement and adjustment design over the lowest possible price.
Configuration matters. The linked UK page showed the Black / Standard version below £300 when checked, while footrest variants were higher. The page also gives conflicting signals about availability, so treat the product page, cart, delivery date, and return terms together rather than relying on a single status label.
Consider it if: you want the Doro back and arm design and can confirm that the selected standard configuration fits both your budget and delivery needs.
Skip it if: adjustable seat depth is non-negotiable and the retailer cannot confirm that control for the exact version you are buying.
IKEA MARKUS: the established simple option
The MARKUS is the sensible comparison for a buyer who would rather have a straightforward high-back chair and a clear after-sale framework than a long list of adjustment controls. IKEA lists manual tilt tension, a 10-year guarantee, a 110 kg test rating, and nearly 3,000 public reviews on its UK product page when checked.
Its trade-off is limited personalisation. The seat height adjusts, but the arms and lumbar position are not presented as independently adjustable. That makes it worth trying if your proportions already work with the chair, and less suitable if you know you need fine control of armrest position, seat depth, or lumbar placement.
Consider it if: you prefer a simple high-back chair, can try it in store or are comfortable with IKEA’s return terms, and do not need highly adjustable arms.
Skip it if: you need a short seat pan, low starting seat height, adjustable armrests, or precise lumbar positioning.
Where to buy and what to check
Do not limit the search to one brand site. Check the manufacturer, Amazon UK, and established UK retailers for the exact model and configuration. A marketplace listing becomes a real alternative only when you can verify the seller, fulfilment route, delivery cost, return deadline, and UK warranty coverage. We do not link an Amazon listing here until those details are visible for the same model.
Use independent testing correctly
Independent test organisations can assess controls, ergonomics, assembly, safety, and sustained sitting in ways a product specification cannot. For example, Which? describes testing chair controls, comfort, assembly, adjustability, and safety with experts and a tester panel. That method is useful context. It is not permission to claim that every chair in this guide received a Which? verdict.
For your own fit check, use our ergonomic chair buying guide. To compare the Sihoo range in more detail, see our Sihoo lineup guide.