The construction changes how you sink, turn and share
Choose pocket springs or a hybrid if you're unsure where to begin: both give you sprung support, with different amounts of cushioning above it. The National Bed Federation's construction guide explains how the spring design and wire gauge affect tension, alongside the height and number of springs.1 Honestly, the trade could spend less time inventing names and more time telling you what's inside.
If you want separate support across a shared bed, look at pocket springs. Each spring works independently, which helps reduce roll-together. You get support where you put your weight without pulling the whole surface down around you. Check the comfort fillings as well: the springs underneath don't tell you how cushioned your shoulder will feel.
If you want cushioning with some spring underneath, start with a hybrid. This usually means pocket springs beneath a substantial foam or latex layer, although there's no agreed trade definition. It's the combination I favour for an undecided buyer. Look for the actual layers, because adding "hybrid" to a name is considerably easier than explaining the build.
If you want stillness and don't run hot, look at memory foam. It moulds around you under pressure and recovers slowly, so movement is less abrupt when someone turns over. It also holds heat. Skip deep memory foam if you already throw the duvet off at night, whatever the cooling claims say. If you change position a lot, check that you can turn without feeling stuck in quicksand.
If you want bounce and can afford it, try natural latex. It comes from rubber-tree sap and returns to shape immediately when pressure lifts, so you can move without waiting for an indentation to fill out. I think it's the best material too many buyers walk past. My one reminder: latex allergy exists, so take that into account if it applies to you.
If you're furnishing a lightly used spare room, consider open coil. Its springs are linked in rows, so movement travels across the surface when someone turns.2 It is generally cheaper and firmer. For your everyday shared bed, spend on pocket springs if the budget allows. Continuous spring uses one wire and feels more responsive than open coil, but remains a linked construction.
If you need an all-foam mattress for a slatted or adjustable base, check the base requirements before choosing. Layers of different-density foam form the whole mattress, and these builds often arrive rolled. A boxed mattress can also contain pocket springs. The box is packaging, not a construction, however enthusiastically someone advertises it.
Firmness labels only help within the same brand
Use a maker's firmness labels to navigate its own range, then judge other brands by construction and feel. According to the National Bed Federation's buying guidance, there is no industry-wide standard for comparing firmness ratings between manufacturers. One maker's medium can feel like another's firm.3 A shared vocabulary would be bloody useful when you're buying something this awkward to return.
For adults with nonspecific low back pain or morning stiffness, a 2026 review of 47 studies by Caggiari and colleagues most consistently favoured medium-firm mattresses over very firm or very soft surfaces.4 This was a qualitative synthesis; no meta-analysis was possible. For that back-pain population, medium-firm is the most consistently favoured place to start, then adjust for your build and sleeping position.
The belief that firmer automatically means better for your back is, to my mind, the trade's most expensive myth. You don't have to demonstrate commitment by choosing something that feels like a paving slab. "Orthopaedic" is used loosely for firmer models and has no agreed meaning. Ignore it as a buying shortcut, and use our back-pain mattress guide if that's your main concern.
Try the hand check as a rough clue alongside comfort. Lying on your back, slide a hand into the hollow beneath your lower back. The trade guidance says that if it slides in too easily, the mattress "may be too hard"; if getting it underneath is a struggle, it's "probably too soft". Pay attention to how evenly you're supported as well as whether the surface feels welcoming.
Use the soft-to-extra-firm wording beside a listing to narrow your browsing, then read about the layers and check the feel. A pleasantly soft top can sit over substantial support. Equally, a firm surface can still dip beneath your hips if the mattress is worn.
Your weight comes before your sleeping position
Start firmer as body weight increases and softer as it decreases, then allow a little more cushioning for side sleeping. That's how I narrow the choice. Your shoulder needs somewhere to go when you're on your side, and lying rigidly straight to impress a sales assistant won't help you choose.
The same trade guidance says heavier sleepers need firmer tension, back sleepers may prefer a firmer feel than side sleepers, and partners three stone or more apart may need different mattresses. Use the table as a shopping steer, then check how you settle into the bed.
My practical starting points for trying mattresses. These are broad comfort guides, and your build and sleeping position still count.
| Your build or sleeping habit | What to try | What to check when lying down |
| Under about 9 stone (57 kg) | A softer feel, with more give if you sleep on your side | Your shoulder and hip can sink into the comfort layer |
| Between about 9 and 18 stone (57-114 kg) | Compare neighbouring tensions within one range | You feel supported without excessive sinking or pressure |
| Over about 18 stone (114 kg) | Firmer tension with a stronger spring gauge | Your hips stay supported and you can turn comfortably |
| Mostly side sleeping | A little more cushioning than for back sleeping | Your spine stays roughly horizontal when viewed from behind |
| Mostly back sleeping | A slightly firmer feel than you would try on your side | Your lower back feels supported without forcing an arch |
| Partners at least 3 stone (about 19 kg) apart | Different tensions or separate mattresses joined together | Each person feels comfortable on their own side |
If you're choosing for side sleeping, concentrate on room for your shoulder and hip. For a heavier build, look more closely at spring gauge and the support underneath the comfort layer. Neither shopping job improves with an impressive-sounding product name.
For a shared bed, try mattresses together so you can check both comfort and movement. A big weight difference is a good reason to investigate split tension or zip-and-link. Compromise is lovely when choosing dinner. With a mattress, different tensions let you each get the support you prefer.
Spend at least ten minutes lying in the position you normally use, because an initial soft sensation is only part of the experience. Turn over as you would at home. In-store testing is most useful for rejecting an obvious mismatch, while a suitable home trial gives you longer to judge everyday comfort.
Measure the bed and read the terms before paying
Measure the frame's mattress space and your delivery route before ordering, then check how returns work. Size names are less dependable than they sound: UK bed sizes aren't standardised, and imported frames often use European sizes.5 "It's definitely a double" is a confident sentence for someone without a tape measure.
Typical UK sizes from the National Bed Federation. Sizes aren't standardised, so measure.
| Size | Width x length |
| Small single | 2ft 6in x 6ft 3in (75 x 190 cm) |
| Single | 3ft x 6ft 3in (90 x 190 cm) |
| Small double | 4ft x 6ft 3in (120 x 190 cm) |
| Double | 4ft 6in x 6ft 3in (135 x 190 cm) |
| King | 5ft x 6ft 6in (150 x 200 cm) |
| Super king | 6ft x 6ft 6in (180 x 200 cm) |
Go larger for two people if the room and budget allow. I'd choose a king over a double before spending extra on fancy upholstery. Allow room to walk around the bed and open the furniture you use, because access to your drawers remains useful after the delivery photographs.
Citizens Advice explains that online orders can be cancelled within the cancellation period that ends 14 days after delivery.6 Tell the seller within that period, then you have another 14 days to send the mattress back. Made-to-measure mattresses carry no change-of-mind cancellation right.
Under regulation 34 of the Consumer Contracts Regulations 2013, the seller can deduct only for any loss in the mattress's value caused by handling it beyond what a shop would allow. Sleeping on it properly is therefore what a comfort trial is for: that's the retailer's own promise, on its own terms, on top of the law.7 Read the refund and collection conditions before buying, and use our sleep-trial guide to check the detail.
If the seller told you before you bought that you'd pay to send it back, you pay. If they didn't tell you, they pay. Citizens Advice explains this, and regulation 35 also says you don't pay for the seller collecting it unless they offered to collect and you agreed to pay.8
Buy the best construction you can comfortably afford, and compare the amount you'll pay with alternatives. I treat crossed-out prices as retail theatre. The discount percentage is much less useful than knowing whether you can afford the mattress and return it under terms you're happy with.
The National Bed Federation says BS 7177 is the British Standard used to demonstrate safety under the General Product Safety Regulations.9 It requires the finished mattress to pass both smouldering and flaming ignition tests. My practical check is to look for BS 7177 on the label or ask the retailer for confirmation. Avoid marketplace mattresses from brands you've never heard of: in my view, you usually can't check the fire label or get a return worth having.
Replace a worn mattress and arrange lawful collection
Replace according to visible wear and how you wake, with age as a loose guide. Seven to ten years is a sensible time to take a closer look, but I disagree with the trade's enthusiasm for replacing by the calendar. You can inspect a mattress without organising its retirement party.
The trade body's replacement checklist asks whether you're sleeping worse than a year ago, whether the bed is older than seven to ten years, and whether you wake stiff or aching.10 It also asks if you sleep better elsewhere and whether there are visible dips or lumps. These are useful prompts to inspect the bed and compare your comfort.
Check the base before placing a new mattress on it. A tired or broken base shortens the new mattress's life, so repair or replace it first. A fresh mattress over broken support is a purchase I would stop you making, even with a very persuasive sale sticker beside it.
Once your mattress is unpacked, don't bend or roll it yourself: the care guidance warns that this permanently damages the spring unit. Factory roll-packed pocket springs are a different matter. I think they're a good advancement, and being delivered in a roll is no reason to reject a sprung mattress. Leave the compression to the factory once you've opened it.
In England and Wales, the household waste duty of care requires you to take all reasonable measures available to you to ensure an old mattress goes only to an authorised person.11 Failing to do so is a criminal offence. Check your council's website for a bulky-waste collection and its fee, or check that another collector is authorised before handing it over.
Pay for a lawful collection and never fly-tip. A cheap collection is poor value if you haven't checked who is taking the mattress, so ask for the waste-carrier details and verify them before arranging pickup.
Avoid the mistakes that make a mattress harder to live with
Avoid these shopping, returns and disposal mistakes before spending anything. Shopping enthusiasm is lovely. Trying to reverse an order for a mattress that doesn't fit is considerably less glamorous, so check the practical details while you're still comparing options.
- Matching firmness words across brands. Compare the construction and how you settle into it, because makers use their own firmness scales.
- Ordering from the size name alone. Measure the frame's mattress space, with extra care for an imported frame.
- Treating cancellation as a free sleeping trial. A comfort trial has its own terms for sleeping on the mattress properly, so read those before ordering.
- Handing the old mattress to an unchecked van operator. Confirm that the collector is authorised to take the waste before collection.
- Putting a new mattress on a broken or tired base. Sort out the support underneath before using the replacement.