“Buy a gel topper for how the foam feels and treat the gel as a bonus that takes the edge off memory foam's warmth in the first hours of the night. If you sleep truly hot, a breathable cover and a cooler bedroom will do more than any amount of gel.”
How the gel is built in
“Gel” on a topper label covers different constructions, and the difference decides how much of it you actually lie on. The most common is gel-infused memory foam, where gel particles or tiny capsules are mixed through the foam as it is made. Panda’s HydroFoam, Luff’s CloudTec and Dunelm’s Gel Fusion work this way, and Origin uses gel-infused beads. The second puts the gel in one layer only, a gel memory foam top over plain support foam, which is how Inofia and JYSK build their 8cm toppers. A moulded gel grid of soft polymer is a third type, but none of the toppers we found in UK sizes uses one.
Spread through 5cm of foam, the gel works across the whole depth but is diluted. Concentrated in a top layer, it meets your body heat first and the support foam below does the holding up.
What gel can and cannot do for heat
Gel works by heat capacity. It takes in warmth before its own temperature climbs, so the surface under you warms more slowly. A sleep-laboratory trial in Physiology & Behavior (Kräuchi et al., 2018) compared a high heat capacity mattress with a conventional one in 15 healthy young men; the high-capacity surface delayed the rise in mattress surface temperature, with a maximum difference of 6.12°C, and increased slow-wave sleep by 16%. A double-blind study of 32 middle-aged men in the journal Sleep (Herberger et al., 2020) found more deep N3 sleep and a slower heart rate on the high heat capacity mattress.
Neither study tested a gel topper, so read them as the principle gel relies on rather than proof for any product here. Once the gel has absorbed what it can, a gel topper sleeps much like ordinary memory foam, which is why Panda states on its product page that its topper “is not actively cooling”.
The bedroom still does most of the work. The Sleep Charity puts the ideal bedroom at around 16-18°C and explains on its advice page for hot nights: “Your body temperature needs to lower slightly before you go to sleep which is why it can be difficult to drop off when you’re too hot.” A gel topper helps at the margin of that.
Cooling gel mattress toppers
Gel toppers are sold on keeping you cooler, and that claim rests on the heat capacity of the gel and on the cover and airflow around it. Our temperature scores follow that build more than the gel itself. The WELLPUR BOKSELVI, with a 3.5cm gel memory foam layer under a polyethylene cooling cover, and the TheraPur ActiGel Cool, zoned gel foam in a wicking polyester cover, both score 8.0 out of 10. The Origin Contour (7.5), the Dunelm Gel Fusion (7.4) with its ventilation holes, the Inofia Cooler Gel (7.3) and the Panda Bamboo (7.2) follow, and the Luff Prestige comes last at 6.8.
A separate gel layer is no guarantee on its own, since the Inofia puts 2cm of gel foam on top and scores below the BOKSELVI. If staying cool is the main reason you are buying, start with the BOKSELVI or the TheraPur, both gel bed toppers with a cover made to move heat or moisture. The Panda ranks first for its dense foam, washable cover and ten-year guarantee rather than for heat.
Depth, density and feel
Choose the depth for the mattress underneath. A 4cm or 5cm gel topper softens a mattress that is firm but still flat; 8 to 10cm suits one that feels hard at the shoulder and hip. Density, where it is published, tells you how much foam you are paying for: Panda quotes 80kg/m³ for its HydroFoam and JYSK 45kg/m³ for the gel layer in BOKSELVI, while most makers give no figure. Our memory foam mattress toppers comparison covers depth in more detail for toppers without gel.
Covers, certification and returns
The foam in a gel topper cannot go in a washing machine, so the removable cover is what keeps it clean. Panda and Dunelm use foam certified under the European CertiPUR scheme, whose label is granted after independent laboratory tests, is valid for three years and is checked with control tests every year. Inofia’s foam carries the separate American CertiPUR-US mark, which requires low VOC emissions of less than 0.5 parts per million. Returns differ more than anything else on this page, because once a topper has been slept on you can usually send it back only within a trial.
For the wider field, including fibre, latex and hybrid designs, see our best mattress toppers guide; if the mattress itself needs replacing, our gel mattress comparison ranks whole mattresses with gel foam.
