We've researched far and wide to help you find the best cot bed mattress for your little one. Chances are you'll have already found the best cot bed for your nursery – but the mattress which baby sleeps on is arguably one of the most important purchases when it comes to getting their nursery ready.
Because while we tend to focus on which style of cot bed or bedside crib suits the nursery best, the best mattress to go inside is a key decision. Cot bed mattresses need to be safe – which means they need to be firm, flat, and be an exact fit for the cot. They should also have good breathability and a waterproof covering (or a separate waterproof protector) so that they can cope with accidents.
Both the NHS and the Lullaby Trust advise that it’s best to choose a firm mattress for babies, so don't be surprised if your mattress arrives and it's a little firmer than you expected. A firm mattress can reduce risk of SIDS, which is also why second hand mattresses are a big no-no for babies. So while you'll want to find a mattress that's comfortable enough for your baby to sleep through the night (fingers crossed), your baby sleeps safest on a firm mattress rather than a softer one.
With so many cot bed mattress options out there, we've put together this handy guide to help make the decision process just that little bit easier. We've selected eight stand-out cot bed mattresses, and put together some useful information and tips at the bottom too, to help you decide on the best one for you and your baby.
Because aside from providing a safe and comfortable bed for your baby, the right cot bed mattress can play a big part in giving the rest of your household a chance at a decent night's sleep, too.
The best cot bed mattresses for 2021
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The great thing about the Little Green Sheep cot bed mattress is that it has two sides; a firmer one for young babies, and a softer side for when they become toddlers. Therefore the mattress is perfect for cot beds, as it will last from birth right up until around the age of 3 (or when your child is ready for a new bed).
What we like
The firm side of the mattress supports small babies and the ‘twist’ in the name comes around the 12-month mark when it’s time to flip the mattress onto the side that's designed specifically for toddler comfort.
While this 70cm x 140cm size fits the majority of cot beds, The Little Green Sheep makes the exact same double sided mattress in smaller sizes too, including an oval shape that fits the Stokke Sleepi.
While its longevity is its biggest selling point, it's also a great natural option, free from synthetic materials, chemicals or fire retardant sprays, giving you peace of mind that your baby is sleeping in a pure and natural environment.
All the materials are breathable, hypoallergenic and free from chemicals and toxins. There's breathable cotton; coconut fibres for support; a natural latex layer for comfort; and a wool layer, which is hypoallergenic and temperature regulating. The core of the mattress is constructed from coconut fibres blended with natural latex that act like ‘thousands of tiny springs.’ The wool layer naturally absorbs and disperses moisture away, creating a clean, dry environment that’s resistant to dust mites & bacteria growth.
The mattress also comes with a five-year guarantee so should easily last until your child outgrows it.
What we don't like
The mattress is not waterproof and does not come with a removable cover, and is sponge clean only. Any nappy leaks or milk will soak through into the mattress unless you buy a waterproof mattress protector for it – which we highly recommend.
We were super impressed with the longevity of The Little Green Sheep's mattress, which already lasts much longer than most cot bed mattresses. Then we came across the SnüzSurface mattress which completely unzips and can be re-configured to suit toddlers and even children up to the age of seven.
The SnuzSurface is the only mattress we've found that offers TripleCore, inter-changeable layers within the mattress that allow you to tailor the level of firmness for your little one's size and weight as they grow. Simply unzip the mattress cover and re-order the layers inside.
While the SnüzSurface isn't made from natural fibres like the option above, it does offer amazing value if it lasts you for several years.
What we like
SnuzSurface cot bed mattress is a great investment, as it's essentially three mattresses in one. The cot bed mattress adapts to provide the optimal level of support for every little sleeper, as they grow from baby to child. The SnuzSurface mattress arrives as a baby mattress, with a firm support that’s recommended by safe sleep experts. As they grow into a toddler and require a slightly more supple sleep surface, just unzip and reorder the comfort layers for a softer sleeping surface.
It's also quite nice and reassuring to be able to see inside the mattress without it being completely sewn up and sealed. Then for the final level of support, re-order the layers to create the most comfortable surface suitable for the increased weight and size of your growing child, up to 22kgs.
The fabric feels very luxurious and soft. You would never guess that the top layer is actually waterproof as it it so soft and not crinkly.
What we don't like
While the mattress is super soft, it's entirely synthetic, so not the best choice for parents who are looking for something more natural. The cover is 100% polyester and the filling is Polyurethane CV foam, steel and polypropylene.
When you take it out of the box and unroll it, you need to leave it to settle for a week so you need to make sure you have it set up in advance. While the mattress is in theory suited to young children, realistically a child aged four to seven will be too tall to still be using a cot bed mattress.
Anything else?
The mattress arrives rolled up in a box, with warning labels that it needs to be unrolled immediately to protect the mattress springs. So if you don't already have somewhere to place or store the unrolled mattress, wait to order it until nearer the time that you need it.
When the mattress unrolls, it takes 7 days to completely flatten out. Don't be alarmed if it appears a bit crinkled and wrinkly at first, the mattress does straighten out.
A cot bed mattress will need to fit a cot bed perfectly, sitting snugly along the sides. When you first place this mattress in the cot bed you'll notice a gap – but after a week of breathing, the mattress will have filled out a bit more.
Eve Sleep is already well known for their quality mattresses, but not everyone knows that they offer cot bed mattress sizes too. The cot bed mattress is essentially a mini-me of its popular memory foam mattress, and is often praised for its cooling properties.
The mattress is made from a mix of springs and foam, is covered in a waterproof layer that protects it from spills, and comes in two standard cot bed sizes (60x120cm or 70x140cm).
The thick, durable foam layer protects the springs and doesn't dip or lose any of that all-important support. Meanwhile the individual pocket springs adapt as your baby wriggles and grows, providing the ultimate support for their body. Springs are also naturally breathable.
The mattress is also super breathable, with a 'Careful 3D fabric' cover which is a highly breathable two-layer material, separated by tiny dividers, encouraging better air circulation to keep your baby as cool as possible.
What we like
The mattress cover is made from a special fabric that makes it super breathable. It's also had a natural antibacterial treatment that promises to keep bugs at bay. But to make sure things stay as clean as can be, it can be unzipped in an instant and popped in the wash at 60ºC.
The cover also has a waterproof laminate layer built in.
What we don't like
There's very little fault to find, but if we had one bad thing to point out it would be that the mattress is made from man-made materials.
Another natural, organic option is the Obaby Natural Coir and Wool Mattress. It sells itself on its natural, chemical-free materials, which protect against dust mites and help regulate your baby’s temperature.
The mattress is made up of a mix of coconut coir – a natural fibre taken from the husk of a coconut – and lambswool. The coconut coir is bonded with latex and is designed to feel like springs. The coconut core is wrapped in lambswool which offers optimum protection against dust mites. Lambswool also helps to regulate babies body temperature, is breathable and prevents moisture building up, plus it's perfect for babies or children who suffer from allergies.
Each mattress comes with a removable cover, made from organic bamboo (which has natural antibacterial properties). This can be unzipped and thrown into the wash.
What we like
It's a great choice for parents who value natural materials but are also budget conscious. Aside from offering a quality and comfortable mattress that's naturally breathable and has natural antibacterial properties, it's also great value and comes with removable cover too.
Choosing a cot bed mattress made from natural materials is ideal for babies and toddlers with allergies, plus when it's time to get rid of the mattress, you can do so with a clear conscience as it is biodegradable.
What we don't like
The only negative we can think of is that this mattress is not double sided, so it offers the same firmness for babies and toddlers.
Great Little Trading Company is predominantly known for its cute kids room storage, rugs, bedding and nursery decor – but they do a great mattress too. Their Nutkin Toddler & Cotbed Mattress has breathable comfort layers and supportive pocket sprung construction, that offer a super comfortable night's rest.
What we like
The cot bed mattress contains a micro pocket spring unit wrapped in breathable fibre and features a breathable and water-resistant cover with an anti-allergy finish that can be washed at 60ºC.
The mattress is one of the more affordable options at just £125 and offers good durability with the removable cover.
What we don't like
The mattress is not double sided, so offers the same firmness for babies and toddlers. This means that it doesn't have as much longevity as some of the other more expensive options above. But it's great for the first year or two, before the baby moves on to a different bed.
Made from 100% natural materials, the Naturalmat mattresses have a natural anti-bed-bug and dust-mite formula, and are also perfect for babies or children with allergies. Parents with babies that suffer from eczema will find it reassuring that the mattresses are treated with essential oils to remove dust mites – no chemicals or toxins which can often flare up skin conditions.
Handmade in Devon, the mattresses are naturally breathable and self-ventilating to help baby regulate their body temperature. The organic coconut fibres are not only breathable and self-ventilating (keeping cool in summer and warm in winter), but ideal for any asthma sufferers.
The mattresses all come with a removable and machine washable cotton cover – ideal for accidents, and for general freshness.
What we like
Being made from natural organic material such as lambswool helps to regulate baby's body temperature easier. So where other mattresses might make babies and children feel sweaty in hot weather, this mattress promises to keep them cool in the summer months, and snug in the winter months.
We also love how well the mattress fits inside the cot bed – they are a perfect fit. While we tested the mattress to fit the Stokke Sleepi Cot Bed (122 x 70 x 9 cm), the Naturalmat mattresses come in an impressive 29 different shapes and sizes – all to fit cribs, cots and cot beds. So whether you have a standard cot, a small bedside crib, a moses basket or a specific shaped cot like the Stokke range or even the semi circle shaped Babybay, there will be a naturalmat mattress that's the perfect fit.
Plus, if your mattress arrives and isn't the right fit for you, naturalmat will exchange it for one that is.
What we don't like
It's not waterproof so you might want to consider a waterproof mattress cover.
The TrueFit™ Premium Mattress is Silver Cross' most luxurious cot bed mattress. It features a higher number of pocket springs (220 to be exact), distributing weight evenly and providing ergonomic comfort and optimal postural support for your growing baby.
The individual pocket springs actively respond to your baby's weight and shape over time, and make the mattress super comfortable, too.
Meanwhile moisture-wicking qualities provide a dry and cool micro-climate as your baby sleeps: There's a waterproof interior, anti-microbial and hypoallergenic properties, heat regulating fabrics and a temperature-regulating exterior with natural Tencel fabric to wick away moisture and promote airflow.
Exclusive to Silver Cross, the True Fit™ design also features unique square shaped corners for a better edge-to-edge fit in your standard cot bed.
Designed to grow with your child, the Premium Cotbed Mattress is fully reversible, providing firm support for infants aged 0-18 months and offering a softer side for toddlers and children aged 18 months and over.
What we like
The mattress gets its 'TrueFit' name from the square-shaped corners which minimise gaps between the cot bed and mattress, keeping little arms and legs safe.
We love that the mattress is reversible for older babies, thus extending the product's life. The design features a firmer sleep side for babies aged 0–18 months, while the softer side offers the best support and comfort for little ones aged 18 months and over.
The mattress feels super soft, padded and comfortable, with a temperature regulating quilted cover that feels fresh and cool to the touch.
What we don't like
We can't think of anything, other than that it perhaps feels a little on the thin side.
This highly rated mattress has received mostly all five-star reviews, with comfort being the recurring theme between reviews.
Similar to The Little Green Sheep mattress, the Mamas & Papas Premium DualCore Cot Bed Mattress can also be flipped. The soft side provides firm support for baby, whilst the pocket sprung side contours and responds to changes in your toddler's shape and size as they sleep.
What we like
In terms of comfort, this mattress has a high count of mini pocket springs plus crush-resistant walls and an additional natural coir support layer, promising a comfortable night's rest.
It's also a very breathable mattress, with temperature regulation and perspiration control – perfect for keeping babies cool. The fibre core lining promotes airflow and keeps baby cool, while a perspiration control treatment reduces the chance of baby sweating.
The mattress is also treated with anti-allergy properties as well as Purotex Technology, to protect baby from bacteria and allergens.
Last but not least, the outer cover is removable for quick and easy washing.
What we don't like
We couldn't think of anything.
How to choose the best cot bed mattress
The key factors to consider when choosing a cot bed mattress are firmness, breathability, and size. We cover firmness and size below, but look out for a breathable mattress that will help keep baby cool.
You also need to consider how easy it is to keep the mattress clean. Ideally, you want one with a waterproof cover, but these can be purchased separately if not provided.
If asthma or allergies run in the family, it's worth checking whether the mattress you're buying is hypoallergenic (memory foam or latex mattresses will be). Otherwise, shop for one with a quilted top layer that can be put on a hot wash to get rid of dust mites. Look out for cot bed mattresses that have Allergy UK approval.
What material is best for a cot bed mattress?
When looking for the best cot bed mattress, you'll find there are lots of different materials to choose from. They all come with their advantages and disadvantages.
There are now a number of organic, natural mattresses made from eco-friendly materials such as wool, coconut coir, natural latex, bamboo and eco fibre. These mattresses are chemical-free, sustainable and bio degradable, plus they're the best option all round for breathability, natural anti bacterial properties and for any babies with allergies.
Foam mattresses on the other hand are much easier to clean than natural mattresses, plus they are more affordable and are lightweight – making them an ideal choice for travel and to fit travel cots.
Memory foam and hybrid mattresses, such as the Eve Sleep cot bed mattress, are slowly becoming as popular for cots as they are for adult beds. They provide good support and modern memory foam (think: hybrid, which = memory foam top layer over springs) has breathability built-in, unlike the original mattresses.
Standard spring mattresses are made of open coil springs surrounded by foam or other materials. These tend to be more durable and supportive than foam mattresses, but this also makes them more expensive.
Coil spring mattresses usually have coiled springs with a top layer of felt and foam. These mattresses tend to be of good quality, offering the right level of support. This makes them a good buy for cots that extend their lives by becoming cot beds as your baby grows into toddlerhood.
In a pocket spring mattress, each spring is individually wrapped in a cloth pocket. This means each coil can move independently, giving excellent support and comfort. While this is one of the best options, it's also one of the most expensive options.
Why does a baby mattress need to be firm?
Both the NHS and the Lullaby Trust advise that it’s best to choose a firm and flat mattress for babies. Experts say the firmer the better in the first six months; and it shouldn't sag. Ideally, look for one that's 8cm to 10cm deep.
A firm mattress can reduce risk of SIDS, as your baby could roll their face into a soft mattress and sink into it, reducing air flow. This is also why second hand mattresses are a big no-no for babies. So while you'll want to find a mattress that's comfortable enough for your baby to sleep through the night (fingers crossed), your baby sleeps safest on a firm mattress rather than a softer one.
What's the best size for a cot bed mattress?
While there is no absolute standard cot, cot bed or bedside crib size, the most common sizes are 60cm x 120cm and 70cm x 140cm. Bedside cribs are usually slightly smaller as they’re designed to last till around six months and are generally around 50cm x 80cm. Always make sure your mattress is the right size for the cot or cot bed you are using and fits snugly to avoid your baby getting their hands or feet stuck down the sides.
It’s recommended that cot bed mattresses are around 10cm thick to avoid sagging where your baby sleeps. Travel cot mattresses are usually thinner, but your baby isn’t expected to sleep on these every night.
Is it safe to use a second hand cot bed mattress?
If you are given a cot by someone else or you buy second-hand, you will need to buy a new mattress even if the existing one appears to be in perfect condition.
Even if you already have a mattress in your home which was used by an older child, it's still best to replace it. The reason why second-hand mattresses are seen as a no-no is because they have been linked to sudden infant death syndrome (SIDS), which is sometimes referred to as cot death. This is because your baby could roll their face into a soft mattress and sink into it, reducing air flow.
There is also the risk a used mattress might be harbouring bacteria or dust mites, which could aggravate any allergies.
How thick should a cot bed mattress be?
For support, your choice of cot mattress should be no thinner than 8cm. However, 10cm is what most experts recommend.
How long should a cot bed mattress last?
Most cot bed mattresses are designed to last until your child has outgrown their sleeping space and moved into a bed.
What depth should a cot bed mattress be?
The NCT recommends that, when the mattress is in position, there’s a minimum 50cm clearance to the height of the cot to prevent a mobile baby from climbing out.
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