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The best king size mattresses you can buy in 2024: Our expert picks, tried and tested

Corner of mattress with brass bed frame a

Want to buy a king size mattress, but not sure which one? We’ve tested the best foam and hybrid king mattresses from Emma, Simba and more

The best king size mattress is a worthwhile upgrade from a double if you share your bed with a partner, or you just value your space. Not only does a king size give you more room, but we’ve found that bigger mattresses isolate movement better and even keep you cooler all night.

But which king size mattress should you choose? To help, we’ve tested more than 40 mattresses of many types, including memory foam and bed-in-a-box hybrids, to measure qualities such as softness, support and temperature control. We’ve whittled down our top favourites to just six mattresses, which you can check out on our best mattress roundup and buying guide.

Alternatively, on this page we’ll reveal our top king size mattress picks in areas including comfort and value for money, and offer useful information such as warranty details and, of course, price.

Looking for a smaller mattress?
Read our guide to the best double mattresses instead.

Deal of the week

Emma is currently running a clearance sale on stock nearing its expiration date, which includes our favourite mattress for couples: the Emma NextGen Premium. If you act fast you can pick one up in a king size from the Emma Outlet for just £443, saving you a massive 40%. 

View deal at Emma

Best king size mattress: At a glance

Best for couplesEmma NextGen PremiumCheck price at Emma
Best hybrid mattressSimba Hybrid ProCheck price at Simba
Best for side sleepersEve Wunderflip Premium HybridCheck price at Eve
Best value for moneyNectar Essential HybridCheck price at Nectar

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How we test mattresses

It may sound obvious, but it’s essential: we test our mattresses by sleeping on them. That’s part of it, anyway. We also put each mattress through tests designed to compare them fairly and precisely, using weights, spirit levels and thermocouple thermometers. Our main focus here is on firmness and temperature control, though we do also measure edge support and motion isolation.

Testing a king-size Hypnia Supreme memory foam mattress

The base your mattress lies on will play its part in how a mattress feels, with a slatted base adding a little more bounce than a solid divan base. We can’t always test multiple bed bases when reviewing a mattress, but we always take this into account when judging.

A mattress is a big investment, so value for money is an important factor. We also take into account delivery experience, warranty details and free trials, which are notably generous in the bed-in-a-box market. After all, you only really know a mattress is perfect for you after you’ve slept on it for weeks or even months.

The best king size mattresses you can buy in 2024

1. Emma NextGen Premium: Best king size mattress for couples

Price when reviewed: £799 (king) | Check price at EmmaEmma NextGen Premium mattress review on a bed frame, in a bedroom

  • Great for… couples needing a more peaceful sleep
  • Not so great for… anyone who prefers a soft mattress

You can snap up Emma’s premium hybrid mattress in a king size for £799 – or less, thanks to the brand’s regular sales. That puts it at the more affordable end of the king size hybrids we’ve tested, but it’s certainly not lacking in quality. When testing, we found a balance of comfort, support and breathability that we had only previously experienced in much more expensive mattresses.

The Emma NextGen Premium is built around an innovative combination of large, supportive pocket springs and assorted layers of foam. This helped to keep us cool, even during the balmy nights of summer. The mattress also delivered superb motion isolation, so we barely noticed when our partners were restless.

Read our full Emma NextGen Premium review

Key features
TypeFoam and pocket spring hybrid (185mm “extra tall” springs, 140mm high-resistance polyurethane foam, 200mm visco-elastic memory foam)
Needs turning?No
SizesFive sizes from single to super-king
Warranty200-night trial, 10-year warranty
Check prices at Emma

2. Simba Hybrid Pro: Best king size hybrid mattress

Price when reviewed: £1,329 (king) | Check price at Simba

  • Great for… top-notch comfort in different sleeping positions
  • Not so great for… a budget choice for the spare room

We found it hard to separate the Simba Hybrid Pro and the Emma NextGen Premium when choosing our favourite hybrid mattress, so much so we’ve got a whole page dedicated to comparing the two. The Emma scored better on motion isolation, while the Simba felt more durable and luxurious. However, the Simba is significantly more expensive than the Emma, so keep an eye out for Simba’s regular discounts.

The Hybrid Pro contains two layers of micro pocket springs and an upper comfort layer made from British wool, plus several layers of foam. This creates an adaptive sleeping surface that we found incredibly comfortable in all sorts of sleeping positions. We also loved the cooling wool layer, which has a lovely cradling effect to offset the firmness of the foam and springs.

We think the king size Hybrid Pro is worth its full price of £1,329, but it’s worth knowing that you get 200 nights to try it out before returning it for a full refund if you don’t get on with it.

Read our full Simba Hybrid Pro review 

Key features
TypeWool, foam and micro pocket spring hybrid
Needs turning?Rotate once/month for the first six months; once every 3/6 months thereafter
SizesSingle to king
Warranty10-year warranty, 200-night trial with money-back guarantee

3. Nectar Essential Hybrid mattress: Best for value for money

Price when reviewed: £650 (king) | Check price at Nectarnectar essential hybrid mattress on an upholstered bed frame, on a grey background

  • Great for… a lifetime warranty and year-long trial period
  • Not so great for… support from edge to edge

Nectar’s Essential Hybrid undercuts many of its bed-in-a-box rivals on price, making this 25cm thick six-layer mattress one of the cheapest hybrids we’ve reviewed. Our tester found this medium-firm mattress offered comfort and support in excellent measure, as well as good motion isolation to give you some peace from a fidgety sleeping partner. Its edge support could be stronger, but if you’re opting for king size you’re unlikely to be squeezed right to the edge of the bed anyway.

What impressed us most was Nectar’s unbeatable warranty. We haven’t been able to test the mattress for a lifetime (yet), but Nectar has such confidence in its product that you get a free lifetime (actually, “forever”) guarantee against faults. You also have a whole year to decide whether you want to keep it.

Read our full Nectar Essential Hybrid review

Key features
TypeFoam and pocket spring hybrid with six layers, including dynamic support layer, pressure relieving foam, encapsulated 15cm pocket springs
Needs turning?No
SizesFive sizes from single to super-king
Warranty365-night trial, forever warranty
Check price at Nectar

4. Eve Premium Hybrid: Best king size mattress for side sleepers

Price when reviewed: £849 (king) | Check price at Evebest-king-size-mattress_eve-wunderflip-premium-hybrid-mattress on a white background

  • Great for… anyone who struggles with the heat of summer nights
  • Not so great for… a larger couple who both need firm support right to the edge of the mattress

The Premium Hybrid is our favourite mattress from Eve’s extensive bed-in-a-box mattress range, impressing our reviewer with its sumptuous 28cm thickness and superb cooling properties, which helped her sleep at the height of summer. Our main niggle was the level of edge support, or lack of it, which means the king size fails to offer quite as much support for a couple as it might. Edges aside, the balance of sink-in comfort and ergonomic push-back is excellent.

Since we wrote our full-length Eve Premium Hybrid review, Eve has relaunched the mattress as the Wunderflip Premium Hybrid and dropped its price from £1,449 to an excellent-value £849 for a king size. We’ll be reviewing the new flippable version.

Key features
TypeFoam and pocket spring hybrid
Needs turning?Rotate once every month or so
SizesDouble to super king
Warranty10-year warranty, 365-night trial period with money-back guarantee

Check price at Eve

5. Origin Hybrid mattress: Best supportive king size mattress

Price when reviewed: £629 (king) | Check price at OriginBed with Origin Hybrid Mattress in decorated room

  • Great for… heavier sleepers who need consistent ergonomic support
  • Not so great for… lighter sleepers who need more softness to sink into

Origin’s Hybrid mattress delivered an excellent balance of comfort and ergonomic support in our tests, with consistent support right across the surface from edge to edge. Our tester found the mattress to be on the firm side, but noted that its clever combination of foam layers provide cushioning where needed.

Like many newer hybrid mattresses, the Origin Hybrid features a grid layer designed to optimise back support, and a latex layer that helps the air flow so you don’t feel too hot at night. Our reviewer also found that the layer of novel “coil system” pocket springs offered better and better support the further you sink into the mattress.

Read our full Origin Hybrid mattress review

Key features
TypeHybrid with six layers, including “HexaGrid” foam, bamboo-infused wool, cooling cover, 3,000 pocket springs
Needs turning?No
SizesFive sizes from single to super-king
Warranty200-night trial, 15-year guarantee
Check price at Origin

6. Hypnia Supreme: Best luxurious king size hybrid mattress

Price when reviewed: £1,625 (king) | Check price at HypniaBed with Hypnia Supreme mattress in bedroom

  • Great for… an investment in years of comfort
  • Not so great for… people watching their pennies

While all-foam mattresses can be great for side sleepers because they have plenty of “give” for the contours of your hips and shoulders, they sometimes lack the ergonomic support and durability you also need for a proper night’s rest. Not so with this premium mattress from Hypnia, which we found to offer a superb level of support from edge to edge.

Supreme by name, Supreme by nature – and Supreme by price too, as this mattress is certainly an investment, with a king size costing over £1,600… unless it’s been discounted in one of Hypnia’s fairly regular sales. But this mattress is a real investment, with a 15-year guarantee and a robust feel that should deliver many years of support without sagging.

Read our full Hypnia Supreme review

Key features
TypeFoam with four layers, including premium memory foam, graphite-infused open-cell foam, multi-zoned support base
Needs turning?No
SizesFive sizes from single to super king
Warranty200-night trial, 15-year guarantee
Check price at Hypnia

7. Tempur Original Supreme: Best premium king size foam mattress

Price when reviewed: £2,050 (king) | Check price at Bensons for BedsBed with Tempur Original Supreme mattress in room

  • Great for… zero-compromise comfort that adapts to your shape
  • Not so great for… affordability and edge support

It may be the priciest mattress on our rundown, but if you’re looking for a memory foam mattress and you don’t want to compromise, there’s nothing quite like the Tempur Original Supreme.

We found this classic mattress to have a unique feel that most of its new-age bed-in-a-box rivals can only aspire to. Its upper layers of foam give relief to your hips and shoulders, while its lower layers provide ample support for your lower back, and the overall effect is one of supreme comfort. By and large, it achieves this without sacrificing support, but our reviewer did find that support weakened towards the edge of the bed.

Read our full Tempur Original Supreme review

Key features
TypeMemory foam with three layers, including 1100mm Durabase, 80mm support foam, 20mm comfort foam
Needs turning?No
SizesFive sizes from single to super king
Warranty40-night trial if bought from Bensons for Beds, 10-year guarantee
Check price at Bensons for Beds

How to choose the best king size mattress for you

How big is a king size mattress?

A standard UK king size mattress measures 150cm by 200cm, compared with 135cm by 190cm for a double. We welcomed the extra sleeping surface when testing, and the taller members of the team were especially keen on the extra wiggle room for their feet.

Perhaps unsurprisingly, we found some of these king size mattresses extremely heavy. That said, many bed-in-a-box mattress companies go the extra mile on delivery, with helpful drivers who’ll deliver your mattress directly to your bedroom and save you doing any lifting.

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