Sofa Bed, Cot and Special Size Mattresses

Some beds refuse to follow the rules. There is the sofa bed whose folded mechanism leaves an awkward gap, the cot that measures 60x120 on the card but not in the frame, the antique bed inherited from a grandparent, and the narrow alcove that fits nothing on a shop floor. Standard mattress sizes cover most of life, but the exceptions are where buyers get stuck, and where a mattress that is two centimetres wrong becomes a daily annoyance.

Special size mattresses are not a niche for enthusiasts. They are what you need whenever a frame is unusual, whether that is a sofa bed used by guests every month, a next-to-me crib by the parents' bed, or a cabin bed in a child's small room. Getting the measurement right, and choosing a build that suits the occasional or unusual use, is what turns an awkward frame into a comfortable bed.

This guide works through the common special cases, from sofa beds and cots to the French and one-and-a-half sizes that confuse buyers, and explains why the Luxury Relax range offers made-to-measure options that keep a proper support core even when the dimensions are unusual.

Measuring a Non-Standard Frame Properly

The single most common mistake with a special size mattress is measuring the old mattress instead of the frame. An old mattress has compressed and stretched, so it tells you what once fit, not what fits now. Measure the internal dimensions of the base at the widest points, from the inside edge of one side to the inside edge of the other, and repeat at both ends in case the frame is not perfectly square.

For sofa beds, the mechanism decides the usable area. Measure the sleeping platform when it is fully unfolded, and check the depth clearance around it, because a mattress that is too thick may stop the bed folding back or hit the frame when it closes. A hinged sofa bed also needs a thinner, more flexible mattress than a fixed bed, since it must bend without cracking or losing shape over time.

For cots and cribs, exact fit matters most. A cot mattress must fill the base with no gaps where a small limb could slip, so measure the internal base and order to that measurement rather than to the nearest standard. A next-to-me crib is even more specific, often with a curved or angled side, so the mattress has to be shaped to the frame rather than trimmed to fit. Our children's mattress guide covers the cot and first-bed details.

Sofa Bed Mattresses: Thin, Supportive and Durable

A sofa bed mattress has a hard job in a small package. It must be thin enough to fold or store, firm enough to support a whole adult, and durable enough to survive being folded and unfolded for years. The usual mistake is buying the cheapest foam slab, which feels acceptable on the first night of a visit and turns into a trench by the third.

The right build uses a firm, higher-density foam core rather than a soft one, because on a thin mattress the core is doing all the support work. A memory comfort layer can be added on top if the mattress is thick enough, but the priority is the core. Too much softness in a thin mattress means the sleeper feels the base beneath within minutes.

A protective, washable cover is especially important on a sofa bed, because it spends most of its life under cushions gathering dust and comes out only when guests arrive. A removable cover you can launder keeps the mattress fresh between uses, and an anti-mite treatment helps if it lives in a living room or a spare room that is rarely aired. Our special sizes guide style reference on standard dimensions helps you check what the frame actually needs.

Cot and Nursery Mattress Sizes

The standard cot size is 60x120 cm, and it is the most common nursery dimension in Europe. A cot mattress must be firm, because a soft surface does not give a baby the support a developing spine needs, and it must fit the base exactly, with no gaps at the sides. When people ask for a firm cot mattress, that is the reason: not comfort, but safety and posture.

A next-to-me crib, designed to sit beside the parents' bed, uses its own narrow dimensions and often an angled profile. These mattresses are typically firmer still, because they are used for newborns, and they must be shaped to the frame rather than cut to fit. The one-size-fits-all approach fails here, which is why made-to-measure cradles are common.

A cot mattress should also be breathable and anti-mite, because a baby sleeps close to it for long stretches and cannot adjust a warm surface. A removable, washable cover turns the inevitable spills into a machine wash, and an open structure lets air move, which keeps the surface drier. Parents choosing for a child's first bed can weigh the options with the mattress buying guide.

The Sizes That Confuse Buyers: French and One-and-a-Half

Two sizes trip up more buyers than any others. The one-and-a-half or small double, usually around 120x200 cm, sits between a single and a full double. It is common in guest rooms and larger single rooms, and it offers one sleeper real width without demanding the space of a double. A 120x200 mattress is comfortable solo but still tight for two adults who move at night.

The French size, sometimes 140x190 or 140x200 depending on the maker, is the compact double found in many older European homes. It is a true double but on the small side, and it is often the only size that fits a period bedroom. Buyers who assume the French size is the same everywhere discover that dimensions vary, which is why measuring the frame is essential.

Beyond these, there are bunk bed sizes, cabin bed sizes, camper and caravan beds, and the arched or shaped mattresses found in some boats and caravans. Each has its own logic, and each rewards measuring twice. Where a standard size is close but not exact, made-to-measure removes the guesswork and guarantees a mattress that sits flat and safe.

Why Made to Measure Beats Forcing a Fit

A mattress that is slightly wrong never settles. A centimetre too wide and it buckles against the frame; a centimetre too short and it slides, leaving a gap at the foot that catches limbs and bedding. On a sofa bed, a small excess can stop the mechanism folding. On a cot, any gap undermines the whole point of the fit.

Made-to-measure mattresses are built to your frame's exact dimensions, so they sit flat, support evenly and last longer because they are not being stressed against an ill-fitting base. The process is simpler than many buyers expect: measure the base, order the size, and choose the layer build as you would for any mattress. The result is a mattress that works with the bed rather than fighting it.

The other advantage is that a made-to-measure order keeps the quality you would want in the first place. Rather than accepting a cheap foam slab because it is the only thing in the unusual size, you can specify a genuine support core, a comfort layer and a washable cover. That is the difference between a special bed you tolerate and one you actually enjoy using.

Made to Measure With Luxury Relax

Luxury Relax offers made-to-measure mattresses that apply the same build as the standard range: a thermosensitive memory layer over a high-density Confortgel base, a breathable 3D perimeter band, an anti-mite and hypoallergenic treatment, and a washable aloe cover. The core philosophy does not change because the dimensions are unusual, which is exactly what a special size needs.

The standard range itself shows the quality on offer, from the Venere at €149 and the Elisir at €179 through the Gold at €399 and the Platinum at €699 to the Athena at €990. Every model carries a ten-year warranty and ten trial nights on a satisfied-or-refunded basis, with free delivery and payment on delivery, and the made-to-measure service extends the same standards to a non-standard frame.

A sofa bed, a cot or an awkward alcove is not a reason to settle for a poor mattress. It is a reason to measure carefully and order precisely. Open the contact page to request a free consultation, share your frame dimensions, and get a made-to-measure recommendation that fits the bed you actually have.

Frequently Asked Questions

What size is a standard cot mattress? The common standard is 60x120 cm. Measure the internal cot base exactly, because the mattress must fill it with no gaps where a small limb could slip.

What size mattress fits a sofa bed? Sofa beds vary, so measure the sleeping platform when fully unfolded. A thin, firm, foldable mattress is usually required, and its thickness must allow the mechanism to close.

How big is a French size mattress? Around 140x190 or 140x200 cm depending on the maker, so dimensions differ. It is a compact double suited to older European bedrooms; always measure the frame before ordering.

What is a one-and-a-half mattress? A small double, usually around 120x200 cm, that fits between a single and a full double. It gives one sleeper real width and is common in guest rooms.

What mattress size is used for a next-to-me crib? Next-to-me cribs use their own narrow, often shaped dimensions rather than a standard size. These mattresses are firm and made to the specific frame, so measure rather than guessing.

Can I get a mattress in a non-standard size? Yes. Made-to-measure mattresses are built to your exact frame dimensions while keeping a proper support core and washable cover, which is better than forcing a near-standard size into the wrong bed.