The sofa beds worth sleeping on are the ones whose spec sheet gives a mattress depth and a mattress width, and both numbers are bigger than you’d guess from the photos. Anything sold as a “double” with a 12cm mattress is a guest bed for two nights. A 20cm-plus foam mattress is the start of something you could sleep on for a fortnight. If it’s second-hand, the fire label is the third thing to check, and it decides whether you buy at all.
The mattress line tells you more than the fabric line, and it’s usually buried in the specification tab. That’s where I’d start with any listing.
Who is sleeping on it, and how often
This sets the budget and the mechanism, so settle it before reading a single listing.
A guest twice a year can sleep on almost anything for two nights. Buy the sofa you want to sit on and treat the bed as a bonus. A thin pull-out mattress with a topper kept in the wardrobe is plenty.
A guest for a week, or a partner’s parent who visits every month, needs a real mattress. That means depth, and depth is what makes sofa beds expensive and heavy.
You, every night, in a studio or in a flatshare where your room is also your living room: you’re buying a bed that folds, not a sofa that opens. Comfort as a sofa comes second. The mechanism has to survive being worked twice a day for years, and the mattress has to be one you’d accept on a normal bed. This is the case where I’d spend the most, and look hardest at the second-hand market for something that was expensive new.
Mattress depth: 12cm and 23.5cm are different products
Two listings from the same retailer show the range. A typical velvet three-seater “double” sofa bed, this one at Dunelm, lists a mattress of 182cm long by 132cm wide by 12cm deep, folded inside a sofa 183cm wide and 90cm deep. A click-clack “large double” from the same shop lists a foam mattress 215cm long, 112.5cm wide and 23.5cm deep.
Twelve centimetres is a mattress you feel the frame through by the second night. It has to fold up inside the sofa seat, and that’s what limits it. Twenty-three and a half is a proper foam mattress, and the reason it can be that thick is that the click-clack doesn’t fold it at all: the mattress is the seat and back cushion, and they simply lie flat. I hadn’t realised the two mechanisms put such different ceilings on the mattress until I put the two spec sheets side by side.
So read depth first. Under 15cm, it’s a guest bed. Over 20cm, it’s a candidate for regular use. In between, buy a topper and lower your expectations.
Bed width: measure the mattress, not the sofa
The word “double” on a sofa bed doesn’t mean 135cm, which is what a standard UK double mattress measures. Look at the two examples again. The 12cm mattress is 132cm wide, close to a real double. The deep click-clack, sold as a “large double”, is 112.5cm wide, which is nearer a small double, because the sofa arms take the rest.
That 20cm difference is the difference between two adults sleeping and two adults lying still. For one person, 112.5cm is generous. For two it’s a compromise you should know about before it arrives.
Length matters too. At 182cm, a tall guest will have feet over the end. The 215cm one has room to spare.
Retailers put the sofa’s overall width in big type and the mattress dimensions in the specification tab. The sofa width tells you whether it fits the wall. The mattress width tells you whether it fits the people. Only one of those is on the product photo.
Photo: Max Vakhtbovych via Pexels
Mechanism: click-clack versus pull-out, and the floor each needs
A click-clack folds the back down flat so the whole sofa becomes the bed. The bed is the same length as the sofa and needs about 90cm of clear floor behind it, or the sofa pulled out from the wall by that much, because the back swings down. It’s quick, has no separate mattress to store, and is usually the deeper mattress. As a sofa it tends to be firm and upright.
A pull-out has a folded metal frame and a thin mattress under the seat cushions. The bed comes out in front of the sofa, so it needs roughly the length of the bed, about 190cm, clear in front, plus space to stand at the side. The sofa is a better sofa, because the seat cushions are real sofa cushions. The bed is worse, because the mattress has to fold. It’s also heavier, and the frame is where second-hand ones break.
Before buying, put masking tape on the floor in the shape of the open bed and live with it for a day. In a one-bed living room the open pull-out often covers the coffee table, the television stand and the route to the kitchen. If the bed can only be made up after moving two other pieces of furniture, it won’t be used, which is the test I’d run on all furniture in a small flat.
Whichever you choose, the mattress collects the same sweat and dust as any other and airs worse, because it spends its life folded up. It needs the same treatment as the one in the bedroom, and there’s a piece on how often that is actually worth doing.
Second-hand: where the fire label is and when to walk away
The good sofa beds are expensive new and cheap second-hand, because they’re heavy and awkward to move. That makes the used market the sensible place to look for a deep-mattress click-clack, with one check that isn’t optional.
UK upholstered furniture has to carry a permanent fire label. Trading Standards’ guidance on second-hand upholstered furniture says the permanent label “is usually found behind a loose cover at the rear of the furniture or under a seat cushion” and carries a batch code that traces back to the manufacturer. The same guidance says stapled-on labels need “further checks” because they “may have been added at any time”. I didn’t know the label was a legal thing rather than a shop thing until I read this.
So, in the seller’s living room: lift the seat cushion or unzip the back and find the sewn-in label. If there is one and it’s sewn into a seam, fine. If there’s only a stapled swing tag, or nothing at all, walk away.
While you’re there, open and close the mechanism twice, sit on the open bed in the middle and at the edge, and look for a sag in the frame. Then measure the mattress, not the sofa.
Fitting it through the door and up the stairs
Sofa beds are heavier than sofas and don’t come apart much. The frame is steel. A pull-out double is a two-person carry and won’t go round a tight stair turn unless it can be stood on end.
Measure the front door clear width, the narrowest point of the stairs, and any turn on the landing, and compare them with the sofa’s height and depth, not its width, because it goes through on its end or its side. Ninety centimetres deep is the number that stops sofa beds on the stairs of converted houses. If the listing doesn’t give the packed dimensions, ask.
Second-hand, this is where a deal falls apart: the seller’s flat had a lift, yours has a half-landing. Measure before you pay.
Read the mattress line, tape out the open bed on the floor, find the label. The rest of the small-spaces articles start from the same habit of measuring before paying.
