Sleep guide

Do I need a firm or medium firm mattress?

Compare firm and medium firm mattresses by sleep position, comfort feel and value, using three pocket-sprung Mattress Online examples to narrow the choice.

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Last verified: 2026-06-16

Firm vs medium firm: what changes in feel and support

A firm mattress usually gives you a more supportive, stable surface with very little sink, while medium firm keeps that support but adds a little more cushioning. If you want a more on-top-of-the-bed feel, firm is the clearer starting point. If you want a balance of support and comfort, medium firm is often the safer middle ground. In this shortlist, the Bodyshape Boost 1000 Pocket Memory Mattress is medium firm at £254-£509, the Bodyshape Gel 2000 Pocket Mattress is medium firm at £449-£769, and the Silentnight UltraGel 3000 Mirapocket Box Top Softer Mattress moves towards a softer feel at £759-£1,299.

Which sleeping positions suit each firmness level

Mattress Online links firmer support most closely with back and stomach sleepers, while side sleepers are more often guided toward medium firm or medium because the extra give can feel gentler at the shoulder and hip. Silentnight’s guidance broadly follows the same pattern, with many back and front sleepers landing in the medium-firm to firm range depending on how much cushioning they want. If you sleep on your side and want more softness, the Silentnight UltraGel 3000 is the softest comparison point here. If you want less sink and a more stable surface, the two Bodyshape medium-firm models are the better place to start.

How comfort layers change the feel of pocket-sprung mattresses

Because all three examples use pocket springs, the comfort layer does a lot of the work in changing the feel. The Bodyshape Boost 1000 uses memory foam, the Bodyshape Gel 2000 uses gel foam, and the Silentnight UltraGel 3000 uses UltraGel with a box-top style for a plusher surface. The Silentnight page also describes its foam as more breathable than memory foam. That makes it a useful softer comparison if you are deciding whether you want extra cushioning or a more balanced medium-firm feel.

How body weight and bed setup affect firmness choice

Body weight can change how a mattress feels, and Mattress Online says firmer mattresses may suit heavier builds because they reduce sink. Mattress depth matters too: the retailer says depth can affect bedding, toppers and bed-frame compatibility. Before you buy, check whether your base is a divan, slatted frame or adjustable setup, because the same firmness label can feel different once it is on the bed. This is especially worth doing if you already use a topper or need a specific fitted sheet depth.

Signs you may have chosen the wrong firmness

If a mattress feels too firm, you may notice pressure building at the shoulders or hips, especially when lying on your side. If it feels too soft, you may sink too far and lose the steady support you expected. A mattress that feels overly rigid can also be a bad match if you wanted light cushioning, while one that feels too deep or lofty may be awkward with bedding or the height of your bed frame. Those signs usually mean it is worth moving one step firmer or softer on your shortlist.

What the wider guidance and product pages suggest

The main takeaway is that firmness is about feel and sleep position first, not just a label on the page. Mattress Online defines firm as supportive and low-sink, while medium firm is presented as a balance of support and light cushioning. Silentnight’s guidance also places many back and front sleepers in the medium-firm to firm range. On this shortlist, the price spread runs from £254 for the Bodyshape Boost 1000 to £759 for the Silentnight UltraGel 3000, and the visible ratings are 5.0/5 from 1 review, 4.7/5 from 3 reviews and 4.6/5 from 179 reviews. That makes the Silentnight model the strongest review details, but not a universal winner for every shopper.

How to turn the advice into a shortlist

If you want the lowest entry price, the Bodyshape Boost 1000 Pocket Memory Mattress is the budget starting point at £254-£509. It is a medium-firm pocket-sprung option with a memory foam comfort layer, a 100-night comfort trial and a 1-year guarantee, but the review volume is very thin. If you want the middle path between support and comfort, the Bodyshape Gel 2000 at £449-£769 gives you another medium-firm pocket-sprung option with a gel foam layer, a 100-night comfort trial and a 5-year guarantee. If you want the softest and most premium-feeling comparison point, the Silentnight UltraGel 3000 at £759-£1,299 adds a box-top feel, a 100-night comfort trial and a 5-year guarantee, so it is the best fit here for shoppers who want more cushioning rather than a firmer surface.

Mattresses to use as comparison examples

Available Bodyshape Gel 2000 Pocket Mattress

Bodyshape · Pocket Sprung

Bodyshape Gel 2000 Pocket Mattress

from £449-£769.

£449-£769

Sizes tracked: Single, Small Double, Double, Super King

Check latest price
Available Bodyshape Boost 1000 Pocket Memory Mattress

Bodyshape · Pocket Sprung

Bodyshape Boost 1000 Pocket Memory Mattress

from £254-£509.

£254-£509

Sizes tracked: Single, Small Double, Double, King Size, Super King

Check latest price
Available Silentnight UltraGel 3000 Mirapocket Box Top Softer Mattress

Silentnight · Pocket Sprung

Silentnight UltraGel 3000 Mirapocket Box Top Softer Mattress

from £759-£1,299.

£759-£1,299

Sizes tracked: Single, Small Double, Double, King Size, Super King

Check latest price

Retailer details used

Last checked 2026-06-16. 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.

Helpful next reads

Use these related mattresses guides and reviews to turn the advice into a practical shortlist.

Firmness questions

Is a firm mattress always better for back support?

Not always. Mattress Online and Silentnight both frame the choice around support plus comfort, so a medium firm mattress can be a better fit if you want support with a little more cushioning. Back and stomach sleepers are often the best match for firmer feels, but the right choice still depends on how much sink you want.

Who should choose medium firm instead of firm?

Medium firm is usually the safer starting point if you sleep on your side, like a little contouring, or want support without a rigid feel. In this shortlist, both Bodyshape mattresses are medium firm, which makes them useful comparison points if you want pocket springs but do not want the softer box-top feel of the Silentnight UltraGel 3000.

Are firm mattresses better for heavier sleepers?

Heavier sleepers often prefer firmer support because it can reduce sinking, and Mattress Online says that firmer mattresses may suit heavier builds for that reason. Even so, sleeping position and comfort preference still matter, so a heavier sleeper who lies on their side may still prefer medium firm rather than a very firm surface.

How do pocket springs, memory foam and gel-style comfort layers change the feel?

The pocket-sprung base gives the mattresses responsive support, but the comfort layer changes how that support feels. Memory foam usually feels more contouring, gel foam is used here for a slightly different cushioned feel, and UltraGel with a box top makes the Silentnight model the softest and plusher comparison point in this shortlist.

Should mattress depth and bed base compatibility affect my choice?

Yes. Mattress Online says depth can affect bedding, toppers and bed-frame compatibility, so it is worth checking before you buy. That matters if you already use a topper, need a particular sheet depth or have a base that may change how firm or soft the mattress feels once it is in the room.