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Before you buy: the mattress checklist

Ten things to check before you pay, whichever mattress you choose. Tick them off on screen or print the page and take it to the shop.

The mattress

Firmness: trust a test or your own nights, not the label Brand firmness scales are not standard. An Australian independent test found mattresses sold as "firm" that measured close to soft. Use an independent test where one exists, or a trial. Source: CHOICE (Australia), mattress review findings, 24 June 2026.
Certifications each cover one thing CertiPUR-US covers the foam only. OEKO-TEX Standard 100 covers textiles. GREENGUARD Gold tests emissions from the finished product. GOLS and GOTS cover organic content. One does not stand in for another. Source: certipur.us, oeko-tex.com, ul.com.
Foam density says more about wear than firmness does Density and firmness are separate measurements; density is the main sign of how long foam lasts. Source: Polyurethane Foam Association (PFA) technical bulletin.

Size and frame

Compare sizes in centimetres, not names A UK King (150 × 200 cm) is about the size of a US Queen (60 × 80 in, about 152 × 203 cm). Measure the frame you have. Source: Which? size guide (UK, May 2026); Sleep Foundation size guide (US, a review site with shop links). See the size tool.
Check the frame will not void the warranty Many warranties ask for slats about 7.6 cm (3 in) apart or closer, and a centre support for Queen and larger. Source: Retailer summaries. Retailer wording; read the brand’s own warranty text.
For an older sleeper: bed height The top of the mattress at least at knee height makes getting up easier. Source: Rule 8 on the method page.

Trial, returns and warranty

Trial: how long, and what it really costs Note the number of nights, any minimum nights before you can return, the return or collection fee, and whether you must donate it yourself and send proof. Source: Common terms seen in research q4. Terms differ by brand and country; read them on the day you buy.
UK: online cancellation is not a free trial Online orders have a 14-day cancellation right, but a mattress unsealed and slept on may fall under the hygiene exception, and shops have no legal duty to take back a mattress you simply do not like. Source: Consumer Contracts Regulations 2013, reg. 28(3)(a) (legislation.gov.uk); Which?, 16 Feb 2026.
Warranty: how deep a dip counts Many warranties only cover sagging past a set depth, often 1.5 in (about 3.8 cm), measured with nobody on the bed. Stains, missing labels and an unsuitable frame commonly void them. Source: Retailer pages. Retailer wording; read the brand’s own warranty text.

Price

Ignore the "was" price; compare what people actually pay The UK advertising regulator ruled in 2025 that one mattress brand’s crossed-out prices misled buyers, as only about 11% of sales were at that price. In 2026 the UK competition authority made another brand stop using misleading urgency claims. Source: ASA ruling, December 2025 (as reported by law firm Lewis Silkin); CMA announcement on gov.uk, 28 May 2026.

Terms change. Trials, returns and warranties differ by brand and country; read them on the day you buy. This checklist is general buying information, not legal or medical advice. Last reviewed 28 October 2026.

Want the checks that matter for you? Use the chooser and Bed Fit lists the ones that apply.