Best soft mattresses
Soft is the expensive firmness, and every cheap soft mattress is a compromise disguised as a preference.
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This is the one thing the category never explains. Soft costs more than firm to build properly, and the reason is mechanical rather than commercial.
A soft mattress works by letting you sink into it, so it has to form itself around your shape, and every spring in contact with you compresses differently. That requires a high spring count, so each small region responds independently.
With too few springs, regions respond as groups: the heaviest parts of you sink together and the spine bends. That is the hammock effect, and it is what a cheap soft mattress produces.
A firm mattress does not have that problem, because you are not sinking far enough for grouping to matter. So a cheap firm mattress is sound engineering, and a cheap soft one usually is not.
The picks
The pick, if you want one answer
Otty Pure+ Hybrid 4000 Mattress, 8.0 / 10. Four thousand springs beneath a softer surface, which is what soft actually requires rather than a soft layer over too few springs.
| Product | Best for | From | Score |
|---|---|---|---|
| Otty Pure+ Hybrid 4000 Mattress | Best overall | Upper mid | 8.0 / 10 |
| Mlily Supreme 10000 | Softest, and best for couples | Upper mid | 6.9 / 10 |
| Mlily Haluna Natural 4000 | Best natural soft | Mid range | 7.5 / 10 |
| Origin LumbarCloud Mattress | Best soft for heavier sleepers | £797 | 8.2 / 10 |
Otty Pure+ Hybrid 4000 Mattress: Best overall
Upper mid · 8.0 / 10
Four thousand springs beneath a softer surface. This is what soft is supposed to look like: the spring count is there to let each small region respond independently as you sink, rather than a soft comfort layer laid over a spring unit that cannot keep up.
Buy it if
You want a genuinely plush surface with the spring count to support it.
Do not buy it if
You are over about sixteen stone. Plush and heavy is a difficult combination.
Read the full Otty Pure+ Hybrid 4000 Mattress review
Mlily Supreme 10000: Softest, and best for couples
Upper mid · 6.9 / 10
Ten thousand springs in a king is roughly one every 1.7 centimetres, which earns the only 10 out of 10 for motion isolation on this site. Units that small must use thin wire, so this is unambiguously a plush specification, which is exactly right if plush is what you want.
Buy it if
You want maximum contouring and one of you disturbs the other.
Do not buy it if
You need support. At this count each spring is about as thin as a spring gets.
Read the full Mlily Supreme 10000 review
Mlily Haluna Natural 4000: Best natural soft
Mid range · 7.5 / 10
Natural fibres settle into a plush surface, which is part of why hand-built British beds feel the way they do. That means they need a high spring count underneath, and 4,000 is the correct partner. Natural fillings over a low spring count is the wrong combination.
Buy it if
You want a plush surface from natural fibres rather than foam.
Do not buy it if
You cannot turn a heavy mattress. Natural fillings need regular turning.
Read the full Mlily Haluna Natural 4000 review
Origin LumbarCloud Mattress: Best soft for heavier sleepers
£797 · 8.2 / 10
The difficulty with soft and heavy together is that you need the surface to give and the structure beneath to stop you. Thirty-five centimetres with up to 8,000 springs is the only way that works, and this is the cheapest UK route to it by a wide margin.
Buy it if
You want a soft surface and you are of heavier build, which is the hardest combination to buy.
Do not buy it if
You are under about eleven stone. You will not reach the lower layers.
Read the full Origin LumbarCloud Mattress review
How many springs soft actually needs
| Build | Minimum spring count, king | Why |
|---|---|---|
| Under 11 stone | 2,000 | You do not load the springs enough for grouping to show |
| 11 to 16 stone | 3,000 and up | You sink far enough that each region must respond separately |
| Over 16 stone | 3,000 plus 30cm of depth | Surface gives, structure beneath has to stop you |
Below those numbers, a soft mattress is a soft comfort layer over a spring unit that cannot follow your shape, and the result is the hammock effect: hips and shoulders sink together, the waist is unsupported, and the spine bends.
If your budget cannot reach a high spring count, buy firm instead. A firm mattress with a topper is a better outcome than a cheap soft one, because the mattress underneath is still doing its job.
Who soft genuinely suits
Side sleepers, and it is the strongest case. Your shoulder and hip are the widest parts of you and need to sink in for the spine to stay straight.
Lighter sleepers. Under about ten stone, a stated 7 out of 10 feels firmer than 7, because you compress less before the mattress pushes back. Many people who think they want soft are simply lighter than the rating was set for.
Who it does not suit: front sleepers, whose hips sink and whose lower back then arches all night, and heavier back sleepers, whose hips widen the lumbar gap.
The cheaper route to a softer bed
If you have a sound mattress that is simply too firm, a topper is the cheaper answer, and the rule is strict.
Measure the dip first. Lay a straight edge across the mattress and measure the gap at its deepest point. More than about 25 millimetres and a topper will follow it within weeks.
Then choose on heat rather than thickness, because every material that softens more also insulates more. Dense foam changes the most and warms you the most. Wool changes least and manages moisture. There is no topper that changes a lot and cools.
And plan the anchoring on day one: corner straps, or a deep fitted sheet sized for the mattress plus the topper together.
What not to buy
A cheap soft mattress. The central point of this page. Under 2,000 springs in a king, soft produces the hammock effect it was meant to avoid.
A pillow-top to get softness cheaply. The quilted layer compresses on its own timetable, faster than the core beneath, and it cannot be flipped because there is only one soft side.
An all-foam mattress bought as the soft option. Foam conforms, which is not the same as supporting independently, and it runs warm.
A soft mattress if you are over about sixteen stone and sleep on your front or back. The hips will sink and the lower back will follow.
Also considered, and why they are not here
A roundup is only as useful as what it leaves out, so here is what was assessed and rejected for this list.
| Product | Why it is not on the list |
|---|---|
| Emma Original | All foam at £369. Foam conforms rather than responding region by region, which is a different thing from soft done properly. |
| Inofia Cloud-Lux | A pillow-top, which is the cheap route to softness and the reason the top layer wears out before the mattress does. |
| Mlily Haluna Natural 1500 | Natural fillings settle into a plush surface, and 1,500 springs cannot support that for an average build. Right materials, wrong count. |
| Nectar Classic Memory Foam | Scores 6.0. Soft in feel and without the independent response that soft needs to work. |
| Simba Hybrid Essential | Scores 5.2. The entry model of a range, and entry models are where soft is attempted with too few springs. |
How this list is made, and who made it
Independence
No brand pays to appear on this site and no placement is sold. Some links earn a commission if you buy, which never changes a score, an order or a verdict. Several of the lowest scores here are on products that carry commission, and several recommendations carry none.
Who writes this. Kyle Klinkradt has worked in the mattress and bedding industry for over ten years across retail, distribution and brand partnerships, and has handled, sold or assessed products from every major UK bed-in-a-box brand. Every review on this site is written by one person, so the scores mean the same thing from page to page.
What the assessment is. Construction specifications against what they physically do: spring height and where in the mattress it sits, spring count for the size, gauge, whether the base is sprung or foam, foam density where it is published, comfort layer depth and material. Then the commercial terms that decide what you are actually buying: trial against returns policy, guarantee length against the company's UK trading history at Companies House, and the regulatory record.
What it is not. This is not a laboratory. I do not publish pressure-mapping data or claim to have slept eight years on every mattress here, because nobody has and pages that imply otherwise are not telling you the truth. Where a judgement rests on construction rather than long-term use, the review says so.
What gets a product removed. Leaving the UK market, a specification change that makes the review inaccurate, or a corrected fact. Brands that have withdrawn are kept on the site with the score removed rather than quietly deleted, because people still search for them.
See editorial independence, corrections and the author page.
How these were chosen
Every product here has its own review on this site with a score out of 10, and the score is a judgement rather than an average. Nothing appears in a list because it pays more.
A score is against the market, not against its own range. The cheapest mattress in a lineup is usually priced to make the model above it look reasonable, and the flagship of a budget range has risen into a bracket where better brands compete. Both are judged against what else you could buy for the money.
Everything listed can actually be bought in the UK. That is not a given: Casper withdrew in July 2020 and Leesa no longer sells here, and both still appear in current British roundups with affiliate links attached.
I do not pad the list. Where only three or four products genuinely qualify, there are three or four. A list of seven when the category contains four good ones is a list with three bad recommendations in it.
Prices move constantly. Judge the cash price on the day rather than any percentage beside it. See every review on this site or where the real savings are.
Questions people ask
Why are soft mattresses more expensive?
Because soft works by letting you sink, so the mattress must form itself around your shape and each small region of springs has to respond independently. That needs a high spring count, and spring count costs money. Firm does not have that problem.
Is a cheap soft mattress a bad idea?
Usually. With too few springs the heaviest parts of you sink together and the spine bends, which is the hammock effect. A firm mattress with a topper is a better outcome than a cheap soft one.
How many springs does a soft mattress need?
At least 2,000 in a king under about eleven stone, and 3,000 or more above that. Below those numbers you have a soft comfort layer over a spring unit that cannot follow your shape.
Who should buy a soft mattress?
Side sleepers, whose shoulder and hip need to sink for the spine to stay straight, and lighter sleepers, who compress less and find stated firmness ratings firmer than the number suggests.