Available 
Bodyshape Vitality Memory Foam Ortho Mattress
from £189-£359.
£189-£359
Sizes tracked: Single, Small Double, Double, King Size, Super King
Sleep guide
How to choose the right mattress firmness for your sleep style
Match mattress firmness to your sleep position, preferred feel and budget with three firm Mattress Online examples that show how construction changes support.
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Last verified: 2026-07-17
What mattress firmness actually means
Firmness is the feel you notice when you first lie down, but it also affects how much support the mattress gives once your weight settles in. Soft, medium, firm and extra firm are best treated as a comfort scale, not a universal ranking, because the same firmness can feel different in memory foam and pocket sprung designs. In this guide, the Bodyshape Vitality Memory Foam Ortho Mattress from £189 to £359, the Bodyshape Ortho Memory Foam Mattress from £199 to £349 and the SleepSoul Space 4000 Pocket Orthopaedic Gel Mattress from £464 to £544 give you three firm-leaning reference points to compare before checking the live retailer page for current price, size choice and specification details.
Match firmness to sleep position
Sleep position is one of the clearest ways to narrow the choice. Side sleepers usually need enough cushioning at the shoulder and hip, so very firm beds can feel too uncompromising, while back sleepers often do well with medium-firm to firm support if the surface still gives light contouring. Front sleepers generally need a firmer feel to help stop the midsection sinking too far, which makes the three shortlist mattresses more relevant for stomach sleepers and some back sleepers than for anyone who prefers a softer landing.
Consider body weight and partner preference
Body weight and shared-bed comfort can change how a mattress feels in real use, even when two beds share the same firmness label. A lighter sleeper may find a firm mattress feels more supportive than harsh, while a heavier sleeper may prefer a firmer surface that feels more upright and controlled. If you share a bed, compare how much contouring you want against how much stability you need for movement and position changes; the more contouring memory foam Bodyshape models and the spring-led SleepSoul hybrid will not feel identical for couples.
When firmness should not be the only factor
Construction matters just as much as the firmness label. The two Bodyshape options are memory foam mattresses, with the Ortho model described as 17cm of reflex foam plus 3cm of memory foam, while the SleepSoul Space 4000 is a pocket sprung hybrid with gel foam, which gives shoppers a clear foam-versus-spring comparison. Depth also matters for bed frames, toppers and bedding fit, and Mattress Online notes that mattress depth can affect suitability, so it is worth checking the live product page before assuming a firm mattress will also be the easiest fit for your setup.
What the wider research shows
The strongest shopper takeaway is that firmness should be matched to sleep position and pressure relief needs rather than treated as one right answer for every bed. The shortlist is deliberately narrow and mostly firm or orthopaedic leaning, so it is better as a comparison set than as a full map of the market. Review evidence also helps set confidence: Bodyshape Ortho has 4.5 stars from 347 reviews, SleepSoul Space shows 4.7 stars from 32 reviews, and Bodyshape Vitality shows a thin 5-star signal from 1 review, so the public review picture is much stronger for some models than others.
How to turn the advice into a shortlist
If you are choosing on budget, the two Bodyshape memory foam mattresses are the most direct comparison, with the Vitality from £189 to £359 and the Ortho from £199 to £349. If you want the more premium spring-led option, the SleepSoul Space 4000 sits higher at £464 to £544, but it brings 4000 pocket springs, gel foam and a 10-year warranty, so it suits shoppers who want a deeper hybrid feel and are willing to pay more for it. Before buying, check the latest price, size availability, trial terms and warranty wording on the retailer page, because the live offer and variant range can change.
Mattresses to use as comparison examples
Available 
Bodyshape Ortho Memory Foam Mattress
from £199-£349.
£199-£349
Sizes tracked: Single, Small Double, Double, King Size, Super King
Available 
SleepSoul Space 4000 Pocket Orthopaedic Gel Mattress
from £464-£544.
£464-£544
Sizes tracked: Double, King Size, Super King
Retailer details used
Last checked 2026-07-17. The source list below is included to help you check the details behind the comparison. Always confirm the latest price, delivery cost, stock status and product details with the retailer before buying.
- Bodyshape Vitality Memory Foam Ortho Mattress | Mattress Onlineproduct-page evidence for Bodyshape Vitality Memory Foam Ortho Mattress
- Bodyshape Ortho Memory Foam Mattress | Mattress Onlineproduct-page evidence for Bodyshape Ortho Memory Foam Mattress
- SleepSoul Space 4000 Pocket Orthopaedic Gel Mattress | Mattress Onlineproduct-page evidence for SleepSoul Space 4000 Pocket Orthopaedic Gel Mattress
- Mattress Firmness - Sleep Foundationfirmness scale and trade-offs
- How to Choose a Mattress - Sleep Foundationsleep-position firmness guidance
- Side Sleeping - Sleep Foundationside-sleeper pressure point guidance
Helpful next reads
Use these related mattresses guides and reviews to turn the advice into a practical shortlist.
Firmness questions
Is a firmer mattress always better for back sleepers?
Not always. Back sleepers often do well with medium-firm to firm support, but the mattress still needs enough contouring so the lower back does not feel left unsupported. The right feel depends on the specific construction, not just the word firm on the page.
What firmness tends to suit side sleepers best?
Side sleepers often need more cushioning at the shoulder and hip, so a very firm mattress can feel too uncompromising. Many shoppers in this position prefer medium to medium-firm support, or a firmer bed with enough comfort layer to reduce pressure points.
How do memory foam and pocket sprung mattresses feel different at firm settings?
At similar firmness labels, memory foam usually feels more body-contouring, while a pocket sprung mattress feels more responsive and upright. That means the Bodyshape foam models may feel more enveloping, while the SleepSoul hybrid is likely to feel more spring-led even though all three are firm-leaning.
Does mattress depth matter for bed frame or bedding compatibility?
Yes. Mattress Online notes that depth can affect bedding, toppers and bed-frame suitability, so a deeper model like the SleepSoul Space 4000 may need more careful checking than a thinner foam mattress. Always confirm the live depth and size before ordering.
Is a longer warranty the same as better durability?
No. A longer warranty, such as SleepSoul’s 10-year coverage, is a useful confidence signal, but it does not by itself prove a mattress will last longer than a model with a shorter warranty. It is still worth comparing construction, depth and care requirements.