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- Best king size mattress: At a glance
- How we test mattresses
- The best king size mattresses you can buy
- 1. REM-Fit Natural Lux Hybrid: The best overall king size mattress
- 2. Hypnos Inspired By Nature 05: Best luxury king size mattress
- 3. Origin Hybrid mattress: Best supportive king size mattress
- 4. Simba Hybrid Pro: Best premium bed-in-a-box mattress
- 5. Emma Original Pro: Best king size mattress for temperature regulation
- What about the other mattresses?
- How to choose the best king size mattress for you
- Here are Expert Reviews, we’ve tested over 75 mattresses, so you can be sure that we know what we’re talking about when it comes to recommendations for your bedroom
- Our favourite king size mattress is the REM-Fit Natural Lux Hybrid. It’s made from all-natural materials, which means it’s a great choice for those avoiding synthetics such as memory foam
- Alternatively, our top pick for tight budgets is the Origin Hybrid, while one of our favourite mattresses for hot sleepers is the Emma Original Pro
- Our roundup below features king size mattresses for a range of preferences, while our buying guide answers some of the burning questions you might have when shopping for a new mattress
The best king size mattress is the REM-Fit Natural Lux Hybrid, an all-natural mattress free from synthetics such as memory foam. It’s a great option for those looking for a firmer mattress or decent temperature regulation. However, we’re well aware that not everyone will fit into those boxes, which is why our roundup below features mattresses for a range of sleeping styles, needs and budgets.
A 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 they can even help keep you cooler at night, while also having more surface area to isolate movement.
Our expert reviewers have tested over 75 mattresses, so we know what we’re talking about when it comes to recommendations. From traditional pocket sprung to bed-in-a-box models, we’ve selected five of our favourite mattresses from our main best mattress page to feature in our roundup below. And below that, our buying guide addresses the questions you might want answered before you buy.
Best king size mattress: At a glance
| Best overall | REM-Fit Natural Lux Hybrid (£1,100) | |
| Best luxury king size mattress | Hypnos Inspired By Nature 05 (£4,100) | |
| Best on a budget | Origin Hybrid (£538) | |
| Best premium bed-in-a-box mattress | Simba Hybrid Pro (£1,399) | |
| Best for temperature regulation | Emma Original Pro (£799) |
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.
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
1. REM-Fit Natural Lux Hybrid: The best overall king size mattress
Price when reviewed: £1,100 (king size) | Check price at REM-Fit
Reviewed in October 2025 by Jo Plumridge
- Comfortable and supportive
- All-natural materials
- Good temperature regulation
- Too firm for some
While many bed-in-a-box mattresses contain layers upon layers of memory foam and other synthetic materials, the REM-Fit Natural Lux Hybrid is constructed from all-natural materials – including wool, cotton and full-length pocket springs.
As a result, it’s a good choice for hot sleepers, as natural materials are much more breathable than their synthetic counterparts. It performed well in our temperature tests, dropping from 50°C to 27.4°C after ten minutes.
The Natural Lux Hybrid is also comfortable and supportive, with a firmer feel that suits back sleepers and heavier users over lightweight side sleepers. Edge support on the REM-Fit Natural Lux Hybrid is also excellent, for both lying and sitting on.
It’s not necessarily a budget option but – as you’ll soon see – compared to some all-natural rivals, it’s strikingly affordable, starting at £700 for a single and rising to £1,200 for a king. What’s more, we’ve come to expect frequent discounts and offers from a bed-in-a-box brand such as REM-Fit.
Read our full REM-Fit Natural Lux Hybrid review
| Key features | |
|---|---|
| Type | Bed-in-a-box hybrid |
| Needs turning? | Rotate every three months |
| Sizes | Small single to super king |
| Trial period | 100 nights |
2. Hypnos Inspired By Nature 05: Best luxury king size mattress
Price when reviewed: £4,100 (king size) | Check price at Bensons For Beds
Reviewed in May 2026 by Jo Plumridge
- Supremely comfortable and supportive
- Excellent materials
- Very, very expensive
- Short exchange-only trial period
While the REM-Fit Natural Lux Hybrid is a natural mattress that won’t completely break the bank, this beautifully made mattress from Hypnos sits at the other end of the spectrum. Don’t expect to pay anything under four figures for the Inspired By Nature 05: a single will cost you £3,000, while a king size is priced at £4,100.
A beauty it is, however. It’s constructed from high-quality natural materials, including British wool, latex, springs and blended fruit fibres. Don’t let the latter put you off: this is a brilliantly comfortable mattress. Take it from our reviewer, Jo Plumridge: “To put it bluntly, the Hypnos Inspired By Nature 05 is the most comfortable mattress I’ve slept on.” Following a brief adjustment period, Jo didn’t have a single bad night on it.
It’s quite a heavy mattress, so rotating and turning it might be a challenge for some (the brand recommends doing this on a semi-regular basis), but this task is aided by padded handles stitched into the sides. In short, if you can afford the Hypnos Inspired by Nature, it’s an excellent option.
Read our full Hypnos Inspired By Nature review
| Key features | |
|---|---|
| Type | Traditional pocket sprung |
| Needs turning? | Rotate and turn on a “semi-regular basis” |
| Sizes | Single to super king |
| Trial period | 40 nights (exchange only) |
3. Origin Hybrid mattress: Best supportive king size mattress
Price when reviewed: £538 (king) | Check price at Origin
Reviewed in June 2024 by Sarah Matthews
- Very affordable
- Supportive
- You can’t remove and wash the top cover
Origin’s Hybrid mattress delivers an excellent balance of comfort and ergonomic support. Our reviewer – who, by her own admission, normally prefers a softer mattress – found that it “offered an excellent balance between soft comfort and firm support”. Its pocket springs, which are thicker at the base, sufficiently support both heavier and lighter bodies, while the upper foam layer provides comfortable cushioning for side, back and front sleeping positions.
What’s more, the Origin Hybrid’s support is consistent right across the surface from edge to edge, and motion isolation is excellent.
It’d be nice if you could remove and wash the mattress’ cover. But when a king size mattress costs £538, that’s a trifling complaint.
Read our full Origin Hybrid mattress review
| Key features | |
|---|---|
| Type | Bed-in-a-box hybrid |
| Needs turning? | No |
| Sizes | Single to super king |
| Trial period | 200 nights |
4. Simba Hybrid Pro: Best premium bed-in-a-box mattress
Price when reviewed: £1,399 (king) | Check price at Simba
Reviewed in April 2025 by Jane Hoskyn
- Comfortable and supportive
- Contains wool layers for comfort and temperature regulation
- Expensive
When it comes to the vast array of bed-in-a-box mattresses we’ve tested, the Simba Hybrid Pro is one of the most comfortable and supportive. It’s also notably expensive for a bed-in-a-box mattress, but it’s a worthy investment that will suit a range of sleeping positions.
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 wool layer is particularly effective when it comes to keeping you cool, the material being a naturally excellent insulator.
If the price has given you pause for thought, let us point out that you get a 200-night trial during which you can sleep on the mattress in your own home. If you regret your purchase, you can return it for a full refund (be sure to check the trial terms and conditions). It’s also worth keeping an eye out for occasional deals and discounts from Simba. While these aren’t as frequent as they once were, you can still save during peak deals periods such as Black Friday.
Read our full Simba Hybrid Pro review
| Key features | |
|---|---|
| Type | Bed-in-a-box hybrid |
| Needs turning? | Rotate once/month for the first six months; once every 3/6 months thereafter |
| Sizes | Single to super king |
| Trial period | 200 nights |
5. Emma Original Pro: Best king size mattress for temperature regulation
Price when reviewed: £799 | Check price at Emma
Reviewed in April 2025 by Jane Hoskyn (the Original Pro was previously named the Emma Hybrid Thermosync)
- Great for hot sleepers
- Comfortable and versatile
- Might be too soft for some
For a bed-in-a-box mattress containing several layers of memory foam, the Emma Original Pro is strikingly impressive in the temperature regulation department. Here at Expert Reviews, we’re reluctant to use the term “cooling mattress” without qualification: no mattress will actively cool you down, but a good mattress will aid the body to more easily regulate its temperature throughout the night.
The Original Pro contains a layer of “ThermoSync” foam, designed to draw excess heat away from the body, as well as “extra-tall” pocket springs. While we can’t pinpoint a single cause for the Pro’s “cooling” qualities among its specs, it performed well in our tests, dropping from 30°C to 22.6°C in just four minutes.
It’s a reasonably soft mattress, so those looking for a firm mattress may be better off opting for REM-Fit’s Natural Lux Hybrid. But the Original Pro’s spring-and-foam hybrid structure doesn’t fail to provide decent levels of edge-to-edge support and comfort for a range of sleeping positions.
Read our full Emma Original Pro review
| Key features | |
|---|---|
| Type | Bed-in-a-box hybrid |
| Needs turning? | No |
| Sizes | Single to super king |
| Trial period | 200 nights |
What about the other mattresses?
Given that we’ve tested and reviewed over 75 mattresses, the roundup above is not an exhaustive list of recommendations. More mini reviews can be found over on our main best mattress roundup. For a quick glance of what else is on offer, though, here’s a list (in no particular order) of some other mattresses we’ve tested and recommended:
- Simba Hybrid | 5/5 Best Buy | Read our review
- Simba Hybrid Luxe | 5/5 Recommended | Read our review
- Simba Hybrid Ultra | 5/5 Best Buy | Read our review
- Simba Earth Apex | 5/5 Recommended | Read our review
- Emma Original | 5/5 Best Buy | Read our review
- Emma Original Elite | 4/5 Recommended | Read our review
- Tempur Ease | 4/5 Recommended | Read our review
- Otty Pure Hybrid | 5/5 Best Buy | Read our review
- Ergoflex 5G | 4/5 Recommended | Read our review
- Eve Original | 4/5 Recommended | Read our review
- Eve Original Hybrid | 4/5 Recommended | Read our review
- Eve Wunderflip Premium Hybrid | 5/5 Best Buy | Read our review
- Nectar Mattress Review | 4/5 Recommended | Read our review
- Dormeo Memory Plus | 5/5 Best Buy | Read our review
- Dreams TheraPur ActiGel Glacier | 4/5 Recommended | Read our review
- Origin LumbarCloud Mattress | 4/5 Recommended | Read our review
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. As a result of logistics and spatial limitations, we can’t guarantee that we’ve reviewed all the mattresses above in a king size. However, we can guarantee that we’ve scrupulously tested every single mattress that we review, taking into account all of the relevant factors: comfort, support, temperature regulation and motion isolation.
Are king size mattresses heavy?
This all depends on the type of mattress. Particularly deep mattresses and those containing layers of pocket springs are going to be naturally heavier than, say, an all-foam mattress. And king size mattresses are inevitably heftier than their double or single counterparts.
It’s important to take weight into account when shopping for a king size mattress: how easy will it be to manoeuvre into your home, and will you be able to flip or rotate it should you need to? Bed-in-a-box mattresses are usually vacuum sealed and rolled up for ease of transportation, and many mattresses have carry handles to facilitate rotating. Also be sure to check out delivery details: some brands will offer a two-man delivery service to your room of choice as part of the cost of the mattress, while this will cost extra for others.
For more mattress advice, be sure to check out our detailed guide over on our main best mattress page.
