Sihoo M18 vs Doro S100: Which Office Chair Is Better?

Choose the Sihoo M18 if you want the lower price, a cushioned seat and lumbar support you can move vertically and forwards or backwards. Choose the Doro S100 if you want a broader mesh seat, four-direction armrests and lumbar support that follows your movement.

At current sale prices, the M18 costs £149.99 and the Doro S100 costs £179.99. The additional £30 for the S100 buys meaningfully better arms, a wider support surface and a deeper recline. It does not guarantee greater comfort.

My specification-based preference is the Doro S100 for larger users and people who change position frequently. The M18 is the safer option for someone who wants direct control over lumbar position and prefers a foam seat.

Quick verdict

Choose the M18 for:

• Lower price
• Foam seat
• Lumbar height and depth adjustment
• A lighter, simpler chair
• Users approximately 150 to 180 cm, based on Sihoo's stated range

Choose the Doro S100 for:

• Wider mesh seat
• Dynamic lumbar support
• Four-direction coordinated arms
• Recline up to 135 degrees
• Larger users within the stated 136 kg limit

Price

Prices checked on 18 July 2026:

• Sihoo M18: £149.99, reduced from £169.99
• Doro S100: £179.99, reduced from £259.99

Both prices are promotional. Compare the actual checkout price and return terms before deciding.

Lumbar support: control versus movement

The M18 uses a smaller lumbar pad that adjusts vertically and horizontally. This lets you place it against the part of the lower back that needs support and reduce how prominently it projects.

The Doro S100 uses two sprung lumbar wings designed to adapt as the user changes position. The support area is larger but the pressure is less directly controllable.

Choose the M18 if you know precisely placed lumbar support suits you. Choose the S100 if you prefer broad contact that follows movement. If lumbar pressure easily aggravates your back, the M18's manual control may be safer.

Seat: foam versus mesh

The M18 has a W-shaped foam cushion with a listed depth of approximately 45.5 cm and width around 51 cm.

The S100 uses a full mesh waterfall-style seat, approximately 42 cm deep and 51 cm wide. Its shallower listed depth may better suit shorter thighs, while the mesh provides ventilation.

Foam generally feels softer and allows more varied leg positions. Mesh stays cooler but can feel firmer, especially near its frame. Neither material is universally better.

Armrests: S100 wins

The M18's arms adjust primarily in height. The S100 uses four-direction coordinated arms intended to remain supportive across reclined positions.

That is a meaningful difference for mouse and keyboard work. Better arm positioning can reduce the tendency to lift the shoulders or reach forwards.

Check whether the S100 arms move too easily for your preferences and whether either chair can approach your desk without collision.

Recline: S100 wins

The M18 reclines to a maximum of approximately 126 degrees. The S100 reaches approximately 135 degrees and its arms coordinate with the backrest.

Both permit position changes. The S100 is better suited to people who use deeper recline for reading or breaks. Neither chair's deepest recline is necessary for healthy desk work.

Headrest and upper-back support

The M18 includes a headrest with height and angle adjustment. The S100 uses a wide integrated headrest and an independent upper-back section.

Headrests mainly matter during recline. During upright typing, neither should push your head forwards. Torso length will determine whether the fixed relationship between the S100's back and headrest fits correctly.

Size and weight

Sihoo states that the M18 works best for users around 150 to 180 cm and supports up to approximately 136 kg. Its fixed seat depth limits fit at the extremes.

The S100 is marketed towards a wider range of body sizes and has a larger support structure, with the same stated 136 kg maximum load. Its seat height is listed at 46 to 54 cm.

The S100 is likely the better shortlist option for broader users. Shorter users should pay close attention to minimum seat height and use a footrest if necessary.

Warranty and returns

Sihoo's M18 page advertises a 30-day return period and three-year guarantee. Confirm the current UK terms for both models, including who pays return shipping and whether assembly affects eligibility.

Keep all packaging during the trial. Returning a large chair without its original box can be difficult.

Which is better for lower back pain?

Neither chair can be declared better for back pain generally. The M18 offers more direct lumbar placement; the S100 offers broader adaptive contact.

The right choice depends on whether your back prefers adjustable focal support or a flexible support surface. Research does not show that one commercial lumbar design treats lower back pain.

Judge whether the chair reduces aggravation, supports multiple positions and lets you work without accumulating pressure. For a wider shortlist at this price point, see our roundup of the best ergonomic office chairs under £300, and if you want a structured way to compare candidates, read how to choose an office chair for back pain.

Final verdict

The Doro S100 is worth the extra £30 if you value better armrests, a broad mesh seat and deeper recline. It has the stronger overall feature set.

The M18 remains the better value for a tighter budget and offers an important advantage: manual lumbar height and depth adjustment. Choose it if you prefer a cushioned seat or dislike lumbar support that follows you continuously.

Whichever model you choose, use the return period. These two chairs differ most in how they feel, which specifications cannot settle. If you want to see how other mid-range chairs stack up, our reviews of the FlexiSpot C7 and IKEA JÄRVFJÄLLET cover further alternatives.

Frequently asked questions

Is the Doro S100 better than the M18?

It has more advanced arms, broader lumbar support and deeper recline. The M18 provides better direct control over lumbar position and costs less.

Which is better for tall users?

The S100 is the stronger first shortlist for larger users, but check seat height, depth and headrest position. The M18's recommended range ends around 180 cm according to Sihoo.

Which chair is cooler?

The S100 has mesh across the seat and back, making it more ventilated. The M18 combines a foam seat with a mesh back.

Do both chairs have adjustable seat depth?

No. The published specifications reviewed do not list adjustable seat depth for either model. Confirm current configurations before purchase.

A chair or desk accessory can reduce an aggravating factor, but it cannot identify why pain persists. If symptoms are recurring or limiting work, read what recurring back pain may be missing or learn about back-pain assessment in Chelsea.