Online Tool Store
· 5 min read
Best 3 Mattress Size Converters Compared
Manesh Jayawardhana
CIO & Co-founder
You are buying a fitted sheet from a shop in another country, or moving a bed abroad, or looking at an IKEA frame and wondering whether your existing mattress will drop into it. The size is written as a word — king, double, queen — and the word means different dimensions depending on who wrote it.
This trips people up because the names are so familiar that nobody expects them to be ambiguous. A US king and a UK king are not the same bed; a UK king is closer in width to a US queen. Continental European mattresses standardise on 200cm length while US queens and kings run 80 inches, which is a couple of centimetres of difference that a fitted sheet will absolutely notice. Getting from a name to actual dimensions is the whole job.
How to judge a mattress size converter
Does it cover all the conventions you need? US, UK, continental European, and IKEA sizing all differ, and IKEA in particular does not always match its local market.
Does it show dimensions in both units? Inches and centimetres, side by side, removes a whole second conversion step.
Does it warn about near-misses? The dangerous cases are the ones that are close but not equal, because those are the ones people assume are the same.
Is it a chart or a converter? A chart is fine if your size is on it. A converter takes the name you have.
The comparison
| Tool | Best for | Free tier | Watch out |
|---|---|---|---|
| Universal Converters bed size converter | Visual comparison across US, UK, EU, and IKEA | Free online tool | Broad coverage means a lot of sizes on screen at once |
| Turmerry international mattress guide | Reference dimensions across many countries | Free to read | Article format, so you scan a table rather than convert |
| Wikipedia: Bed size | Authoritative dimensions with sourcing | Free, no account | Encyclopaedic, with no interactive conversion |
Facts checked August 2026; plans can change.
Universal Converters bed size converter
This is the closest of the three to an actual converter. It compares international bed and mattress sizes visually across US, UK, EU, and IKEA conventions, which is exactly the set most people need — and the visual comparison is the part that makes the near-misses obvious rather than something you have to spot in a table.
Covering that many conventions means a busy screen. If you only care about one pair of countries, you are reading past the rest.
Turmerry international mattress guide
Turmerry’s guide has the widest geographic reach, covering US, Canada, UK, EU, Australia, and Asian sizing in one reference. If you are shipping a bed somewhere less commonly covered, this is the one most likely to have your market.
It is an article with tables. There is no input field, so you are locating your size by eye — fine for a one-off, less good as a tool you return to.
Wikipedia: Bed size
For a dimension you are going to act on — cutting a frame, ordering a custom mattress — Wikipedia’s bed size article is the most trustworthy reference here, because it cites its figures and is maintained against the standards rather than a retailer’s product range.
It is a reference article. Nothing converts, nothing is interactive, and the presentation assumes you know which convention you are looking for.
Mattress Size Converter
Ours takes a mattress size name or a set of dimensions and converts between US, UK, European, and metric conventions. One input, the equivalents across systems, no scanning. It runs entirely in your browser.
Two honest limitations. Mattress naming is not a formal standard in the way that, say, paper sizes are — manufacturers vary, and a “super king” or a “small double” can differ between retailers within the same country. Our figures reflect the common conventions and cannot account for every brand’s own interpretation. And the converter handles the mattress, not the depth: a fitted sheet also has to accommodate mattress thickness, which varies enormously and is where most sheet-buying disappointment actually comes from.
Which one to pick
- If you want a visual comparison including IKEA sizing, use Universal Converters.
- If your market is outside the US, UK, and EU, Turmerry covers the widest range.
- If you need a figure you can build against, check Wikipedia’s cited dimensions.
- If you have a size name and want the equivalents immediately, use ours.
How to do it with Mattress Size Converter
- Open the Mattress Size Converter.
- Enter the size name you have, or the dimensions if you have measured.
- Read the equivalents across US, UK, European, and metric conventions.
- Measure your actual mattress before ordering anything fitted. More converters are in the tools directory.
You might also need
- Room Measurement Mapper — to check the bed fits the room before it arrives.
Frequently asked questions
Is there a free mattress size converter that doesn’t need an account?
Yes — all three references above are free without registering, and ours requires no account because the site has no signup at all.
Is a UK king the same as a US king?
No, and this is the most common and most expensive assumption in the whole category. A UK king is narrower than a US king and closer in width to a US queen, so bedding bought for one will not fit the other properly.
Are European mattress sizes standardised?
More consistently than in the English-speaking markets — continental European mattresses commonly standardise at 200cm long — but “standardised” here means conventional rather than legally specified. National standards bodies such as ISO publish dimensional standards for many products; bed sizes in practice remain a matter of market convention, so measuring is still the safe move.
Final thought
Convert the name, then measure the mattress. The names are close enough between countries to feel equivalent and different enough to leave you with a sheet that will not tuck.