Best king size mattress toppers

“On a king, choose the topper for the warmer or heavier of the two of you, and read the trial terms before the price, because a topper that has been slept on rarely goes back.”

A UK king topper measures 150x200cm

A king size mattress topper for a British bed should measure 150x200cm, the king size given in the bed size guide from Bed Advice UK. A continental king is 160x200cm, and some shops, Panda among them, sell both, so pick the option labelled UK King. Bed Advice UK points out that a 135cm double leaves each person 67.5cm and warns that “with so little room to move, you’re more likely to disturb your partner every time you change position, resulting in a poor night’s sleep.” A king gives each of you 75cm. A 180cm bed needs a super king topper instead, and a 135cm bed a double topper.

Two sleepers change what matters

On a shared bed one topper serves two bodies and often two temperature preferences, and it decides how much of a partner’s turning reaches you. Slow memory foam, as in the TEMPUR ONE and the Panda Bamboo, tends to mute a partner’s turning, while the springs in the Simba Hybrid Essential and the Dormeo Octasmart Plus feel livelier.

If you weigh very differently, choose for the heavier sleeper, who compresses the topper further. The best evidence on firmness points to the middle. In a randomised trial of 313 adults with chronic low back pain published in The Lancet (Kovacs and colleagues, 2003), people given medium-firm mattresses had better outcomes for pain in bed after 90 days than those on firm ones (odds ratio 2.36). A 5 to 9cm topper is a cheaper way to move a firm king mattress towards that medium-firm feel.

Heat is the third question. A review in the Journal of Physiological Anthropology (Okamoto-Mizuno and Mizuno, 2012) reports that in real-life conditions with bedding, heat exposure increases wakefulness and reduces deep and REM sleep. Dense memory foam holds body heat, so if either of you wakes up warm, favour the John Lewis British wool, the Emma Original Pro graphite foam or the Dunelm ventilated gel foam over dense memory foam.

The ranked king toppers side by side

Regular prices at each merchant’s UK shop, checked on 28 September 2026. At those prices the step from double to king ranges from £5 on the Silentnight to £100 on the TEMPUR ONE. *Emma’s buy box lists 100 nights and up to 10 years, while the FAQ on the same product pages says 30 nights and 2 years. The rest of Panda’s range is compared in our best Panda mattress toppers.

Depth, filling and grip

The Bed Advice UK topper guide suggests a topper at least 5cm deep, because anything thinner is unlikely to make a noticeable difference, and recommends non-slip backing or elastic corner straps so it does not shift on a mattress this wide. Feather and down, as in the Soak&Sleep, adds softness rather than support. Quilted fibre such as the Silentnight Deep Sleep Ultimate 500 is closest to what many shops call a king size mattress pad. The Panda names OEKO-TEX Standard 100, whose label means every component has been tested against a list of over 1,000 harmful substances. For single to super king sizes in one list, see our best mattress toppers.

Topper, protector or both

A topper does not replace a mattress protector, and it needs protecting itself. A king size protector goes on top of the topper, and Bed Advice UK suggests owning two so one can be washed while the other is on the bed. A 9cm topper on a 25cm mattress needs a protector and fitted sheet that fit 34cm. Our best mattress protectors ranking compares waterproof and cotton options.

Check the trial before the price

Once a topper has been slept on, most sellers will take it back only if it is faulty or covered by a sleep trial, so the trial is your way out if the king feels wrong. Simba and Dormeo give 200 nights, Emma lists 100, Panda and TEMPUR 30, and Dunelm, John Lewis, Soak&Sleep and Silentnight offer none on these toppers. A trial will not save a worn mattress either. Bed Advice UK notes that a topper quickly moulds to the dips of a sagging mattress, so that bed needs replacing rather than topping.

Which king topper for which couple