Dormeo Octasmart Plus Mattress Topper reviewed

The Dormeo Octasmart Plus Mattress Topper is a 7cm medium-feel topper with a memory foam top layer, 4cm of Octaspring foam springs in three support zones and a foam base, in a removable cover you can wash at 40°C. The regular price is £249 for a UK double, and at the time of writing (28 September 2026) Dormeo had cut the single to £179, the double to £199, the king to £259 and the super king to £319. Dormeo’s page for the topper shows an average of 4.3 out of 5 from 1,895 reviews.

Layers

The king-size Octasmart Plus topper page on dormeo.co.uk describes three layers, the same idea as the Octasmart Plus mattress in a thinner package.

When a topper is the right fix

Bed Advice UK, the consumer site of the National Bed Federation, sets two useful rules in its mattress topper guide. A topper should be at least 5cm deep to make a noticeable difference, which the Plus clears at 7cm, and it is not a quick fix for a mattress that is past its prime: on a mattress with deep dips, the topper will simply follow them. The same body recommends replacing a mattress every seven years, and research backs up the cost of waiting. In a study of 59 adults in the Journal of Chiropractic Medicine (Jacobson et al., 2009), whose own beds averaged 9.5 years old, sleep quality improved significantly after switching to new medium-firm bedding.

On a mattress that is sound but too firm, the Plus topper is a good choice. We score it 5 out of 10 for firmness, with the zoning placing firmer Octasprings under the hips. Dormeo’s king-size listing says the Octavent air system makes the topper eight times more breathable and cools the bed by 3°C; those are its own figures, and it does not publish the test behind them. The same listing suggests the topper for a guest bed, sofa bed or futon.

Prices by size

Trial and warranty

The topper is covered by Dormeo’s 200-night trial, which starts on delivery and requires the topper to be unpacked within 30 days. The Octasmart topper warranty covers the core for eight years and the removable cover for one, but only the first two years are full cover; from year three you pay a rising share of a replacement, 45% in the fourth year. Dormeo quotes free delivery in 2 to 3 days.