The Complete Mattress Buying Guide

Start at medium-firm: firmer isn't better for your back

"Firmer is better for your back" is the most expensive misunderstanding in the trade. Kovacs and colleagues randomly gave 313 adults with chronic low-back pain a firm or a medium-firm mattress.¹ After 90 days, the medium-firm group did better for pain in bed and disability. The trial had no soft mattress, so it compares medium-firm with firm only. A 2021 review by Caggiari and colleagues of 39 articles concluded that a medium-firm mattress promotes comfort, sleep quality and spinal alignment.² A 2025 sleep-lab study by Hu and colleagues found mixed results for firm mattresses, though it was small, with just twelve people.³

Brands set their own firmness labels: one maker's medium is another's firm. That is maddening when you're trying to compare mattresses, and there's no good reason you should have to decode the labels. Treat firmness labels as a rough guide within a brand, because they don't transfer between makers. Ignore "orthopaedic" too: it's an unregulated word that usually just means firm. A grand word for a hard bed.

My rule of thumb is a buying guide, not a clinical threshold: start at medium-firm if you sleep on your back or in a mix of positions. Side sleepers start a notch softer. Front sleepers start a notch firmer. Then adjust for weight: go a notch softer if you're under about 9 stone, or a notch firmer if you're over about 18 stone. Use the firmness chooser to find that starting point for your weight and usual sleeping position.

This is a starting point, not a prescription. If you share with someone much heavier or lighter, buy for the heavier person and let the lighter one add a topper on their side.

How you sleep changes the mattress you need

On your side

Your hip and shoulder carry your weight over small areas, so they need to sink a little for your spine to stay straight. Too firm, and your shoulder gets pushed up. Your pillow matters as much as the mattress here: use the pillow height tool to choose the height that suits you, because softer cushioning changes how far your shoulder sinks.

On your back

The curve of your lower back needs support, with your hips held roughly level with your shoulders. Avoid anything that lets your hips sink lower, even if the cushioning feels comfortable at first. A hammock belongs in the garden. Choose enough give to support that lower-back curve without letting the heavier part of your body sink too far.

On your front

This is the one position I'd try to talk you out of: keeping your hips supported while your neck is turned to one side is awkward. If changing position isn't happening, choose a firmer mattress to keep your hips from sinking, and use a thin pillow. Your neck is already turned; a thick pillow adds lift you don't need.

A bit of everything

Springs or latex let you turn more freely, so choose a responsive mattress if you change position through the night. Deep memory foam moulds around you, and getting out of that hollow can feel like climbing out of quicksand. Give ease of movement as much attention as cushioning: you need to feel comfortable in each position and be able to leave it.

A pocket-sprung hybrid is the safe default

Pocket springs with foam or latex on top give you cushioning over a spring unit, which makes a hybrid my default when you don't know what you want. No construction is best for everyone, and plenty of mattresses mix materials. Choose by how you want the mattress to feel; the category name alone won't settle it.

Pocket springs

Each pocket spring sits in its own pocket and moves on its own, so one person turning doesn't roll the other towards them. Air moves through the spring unit too, which helps it sleep cooler. Ignore spring counts above about 1,500 in a king: beyond that, the total is a marketing number. The wire, layers and fillings matter more. The trade would have you counting springs in your sleep if it could.

Hybrid

Pocket springs under foam or latex make hybrid mattresses the best all-rounders. The top layer changes the cushioning, so two hybrids needn't feel alike. I sleep on an Origin Hybrid Pro in a king myself. Check the edge when choosing yours, because a saggy edge turns a double into a small double. You should be able to use the width you've bought without feeling that you need to retreat towards the middle.

Memory foam

Memory foam absorbs movement, so it's great for couples who don't want to feel every turn beside them. That close cushioning feels lovely around a hip or shoulder. It sleeps warm, whatever the cooling claim says, so don't pay extra on the strength of a chilly name. Choose it if you enjoy being closely cushioned. Skip deep memory foam if you dislike sinking into a hollow that takes effort to turn out of.

Latex

Latex is the best mattress material most people never try. It's bouncy and sleeps cooler than memory foam, with cushioning that responds as you move. It also lasts for years. The price puts people off, which is understandable when you're already facing a substantial purchase, but it deserves a place on the shortlist if you like that responsive feel. Latex allergy is real: if you have one, ask your GP before considering a latex mattress.

Open coil

In open-coil mattresses, the springs are wired together, so movement travels across the bed and a trench forms in the middle. They're fine for a guest room or a tight budget; I'd never choose one for a child's bed. My worst mattress was an old Silentnight hand-me-down, already twenty years old. I slept in a divot in that open coil, and blamed its age and construction, not the name.

Avoid pillow tops, euro tops and box tops: the soft layer sewn on top softens first and can't be turned over. Check the depth too. Above about 30cm, ordinary fitted sheets stop fitting, and the extra depth is often cheap foam. Buying sheets shouldn't require a specialist search. A double-sided mattress you can turn lasts longer; "no-turn" is a cost-saving dressed up as a feature.

Hot sleepers should choose springs and natural fillings

Foam stores heat because there's nowhere for it to go; springs let air pass through, so choose a spring mattress if you regularly wake up too warm. Natural fillings such as wool and cotton sleep cooler and drier. Look for those materials when comparing mattresses for hot sleepers, and give them more weight than a cooling label. A chilly product name won't make the bed any cooler.

If you must have foam, gel foam is the compromise I'd choose: it seems to make a difference. I'm less convinced by cooling covers and phase-change fabrics. Keep the bedroom cool and try a lighter duvet, because those changes do as much as the mattress. An enormous duvet is quite a lot of insulation to ask a cooling cover to overcome, so check the bedding before spending more on the mattress.

A king is the real double for two adults

Buy the biggest size your room takes, with a king as the starting point for two adults. On a standard double, you get 67.5cm each, less than a child gets in a single at 90cm wide. Buying too small is the most common mistake I see. My partner steals the duvet and turns over a lot, so I'm firmly in favour of giving each other room. Extra width won't get your duvet back, sadly.

Check the room measurements before choosing, because you'll need space around the bed as well as space to sleep.

If you want different firmness, look at split tension or zip-and-link before compromising: the middle-ground mattress leaves both of you slightly unhappy. That's a poor return on being agreeable. With a big weight difference, buy for the heavier person and let the lighter person add a topper on their side. When comparing mattresses for couples, pay particular attention to edge support on anything smaller than a king, because you have less width to spare.

Replace a mattress when it sags, not by the calendar

A lasting sag and how you feel when you wake are the reasons to consider replacing your mattress. Seven to ten years is a loose guide at most. A well-kept old mattress isn't a biohazard, whatever the scare statistics say. Selling you a bed by frightening you about the old one is a grubby tactic. Judge when a mattress is past it by its condition and changes in your comfort.

• Your shape stays printed in the mattress after you get up
• Mornings start stiff and ease off once you're moving
• Hotel beds and the spare room suit you better than your own
• Springs make themselves felt through the top
• You both end up rolling into the middle

Check the base before blaming the mattress: slats more than about seven centimetres apart, or a broken slat, are my first suspects when there's a dip. A new mattress won't repair the base underneath it. A topper fixes "too firm", never "sagging": on a dipped mattress it's a nice layer over a hole. Our advice on a bed that feels too hard helps you work out whether extra cushioning is the answer.

Judge the price per night, never the "was" price

Buy the best mattress you can afford, because you spend a third of your life on it. But afford means afford, and a tight budget needs no apology. Losing sleep over the repayments would be a miserable result from buying a bed. Set a spending limit you can live with, then compare your options within it. The sticker price matters less than what the mattress costs per night over the years you keep it; spending more only makes sense if that longer view works for you.

The "was" price tells you less than it seems. Mattresses are on sale most of the year, so judge the sale price on its own: would you pay that amount without the crossed-out number? I wouldn't let a sale banner decide when to spend that much money. Compare what you're getting for the amount you'll actually pay.

On a tight budget, ask about ex-display models when shops clear seasonal stock. Refuse till upsells such as extended warranties and care packages: you've already got statutory rights and the maker's guarantee. Read the guarantee's sag-depth clause before buying. Every one I've read only pays out once a dip passes two or three centimetres, and none pays for softening. That's a frustrating distinction when the bed feels less comfortable.

Use the showroom to rule things out and the trial to decide

A showroom visit helps you reject a mattress that feels wrong, but tells you little about whether you'll want to keep it. Lie in your usual sleeping position for a full ten minutes, because sitting on the edge tells you very little about sleeping comfort. The polite bounce is not a sleep assessment. Expect to learn what you don't want, and move on if your shoulder feels uncomfortable or turning is difficult.

Trials are the best thing the boxed brands did for the trade. Read the collection and refund terms before buying, then actually use the trial to decide whether you're comfortable at home. Compare mattresses with a sleep trial by those terms as well as their feel. A trial you daren't use is no bargain. Give a new mattress a few weeks, because first nights can give the wrong impression. Check who arranges collection and whether there's any charge to return it.

For online purchases, Citizens Advice says you have a cooling-off period: tell the seller within 14 days of receiving it, then you have another 14 days to send it back.⁵ Personalised or custom-made items are excluded. That's the general online rule; read the retailer's returns and trial terms first for what happens once a mattress is unwrapped. Our checklist of questions to ask before you buy covers delivery, removal and rights in detail.

Plan delivery day, and don't judge it on night one

1. Measure the route. Measure the stairs, the turn at the top and the bedroom door before you order, not on the day.
2. Pay for the extras that matter. Room-of-choice delivery and collection of the old mattress save a back and a weekend.
3. Let a rolled mattress breathe. Give it the full expansion time the maker gives and open a window. The smell is normal and goes.
4. Don't judge it on night one. Your body is used to the old one. Give it a few weeks before you decide.
5. Rotate it. Head to foot every few months, and flip it only if it's double-sided.

A bed-in-a-box mattress left at the front door still needs taking upstairs, so check where the delivery service will leave it and arrange help if you need it. The box is the easy part; getting the mattress into your bedroom is still a job to plan before delivery day.

Some back pain needs a GP, not a mattress

A mattress isn't a treatment for back pain, so don't delay medical help while you shop for one. The NHS says back pain usually improves within a few weeks.⁴ If yours isn't improving, or you recognise any symptoms in the NHS list, follow the advice about getting help.

If your back is stiff when you wake and eases once you're moving, put the bed on the suspect list. Our back pain picks are a place to start when comparing mattresses for comfort. The NHS also advises against staying in bed for long periods, so don't respond to back pain with prolonged bed rest.

Questions people ask about buying a mattress