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11 best cot mattresses to help your little one sleep peacefully

Don’t let choosing the best cot mattress give you sleepless nights. We’ve done the legwork for you so that you (and your little one) can rest easy.

By Mumsnet HQ | Last updated Jan 23, 2023

Baby in a cot

Any parent will tell you that sleep (both yours and your baby’s) is the only thing on your wish list for the first few years of parenthood. So anything you can do to ensure a good night’s sleep for your baby - and for you too - is more than worthwhile. It's our mission to make parents' lives easier, so we've reviewed our fair share of baby beds over the years - take a look at our round-up of the best cribs and best travel cots if you're looking for a better night's sleep. 

An effective cot mattress is about so much more than a good night’s sleep. Like choosing the best baby monitor in your price range, it's about safety and peace of mind. As well as making their cot bed a firm and supportive place for your baby to snooze, the best cot mattresses will also ensure snuffle-free sleep for children with allergies, and help keep them cosy when it’s cold and cool when it’s hot. 

To help you sort through them, we’ve created a guide that taps into the collective wisdom of Mumsnet parents - the biggest online network of parents in the UK - as well as the latest advice from safe sleep experts, feedback from customers and consumer reviews. We’ve researched the best on the market - including mattresses suitable for travel cots, noting which came recommended by experts as well as parents. And each of the mattresses here has been vetted to ensure it complies with the latest safety standards, is firm and robust, and will allow your baby to sleep both safely and comfortably. 

Here are the best cot mattresses to buy in 2023.

1. Best overall cot mattress: The Little Green Sheep Natural Twist Cot Bed Mattress

Price on writing: £199.99 | Buy now from Very

Key specs

Type: Fibre mattress | Materials: Made from 100% natural materials – cotton, coconut, latex and wool | Size: 140cm x 70cm x 10cm; 120cm x 60cm x 10cm

Reasons to buy

  • Multi-award-winning and backed by safe sleep experts
  • Naturally insulating but breathable
  • Hypoallergenic
  • Built to last as your baby grows through the transition from baby to toddler

Reasons to avoid

  • You’ll need to buy an additional mattress protector to guard against spills and accidents

What Mumsnet users say

“Babies need a very firm mattress, but as they get older they might want something slightly softer. So we bought a ‘twist’ mattress which is firm on one side and medium on the other. Expensive, but made from natural materials and good quality so we decided it was worth it.” (Tried and tested by Mumsnet user NameChange30)

Our verdict

Our favourite features? The ingenious composition of this mattress is its biggest selling point. The core of the mattress is constructed from coconut fibres blended with natural latex that act like ‘thousands of tiny springs.' It’s also good for allergy sufferers and is really breathable too.

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 to reveal a solution that’s designed specifically for toddler comfort.

We were slightly disappointed that the cover of the mattress isn’t waterproof or spill-proof, so you’ll need to buy a protective cover if you want the mattress to really go the distance. But in terms of comfort, durability, safety, construction and eco-friendliness, this mattress is consistently name-checked by Mumsnetters. It ticks all the major boxes and should put parents’ minds at ease.

2. Best budget cot mattress: John Lewis Premium Fibre Cot Mattress

John Lewis Anyday cot mattress

Price on writing: £50 | Buy now from John Lewis & Partners

Key specs

Type: Fibre mattress | Materials: Polypropylene cover and recycled PET core | Size: 120cm x 60cm x 8cm

Reasons to buy

  • Excellent value
  • Functional
  • Easy to care for

Reasons to avoid

  • Thinner than most cot mattresses at just 10cm
  • No removable cover

Our verdict

Our favourite features? This fibre cot mattress is only £50, leaving you with plenty for other nursery essentials. And, while it’s not fancy in any way, it does its job well. 

John Lewis is beloved by Mumsnetters for its nursery staples - from baby blankets to moses basket mattresses - and its own-brand range provides excellent quality basics at affordable prices. 

It has a machine-washable cover to make clearing up any accidents easy and for keeping allergens at bay. It’s also made from a micro-pore material, which increases breathability, helping to keep your baby cool and comfortable all night long. 

3. Best breathable cot mattress: Eve the cot mattress

eve sleep cot mattress

Price on writing: £150 | Buy now from Argos

Key specs

Type: premium pocket springs with supportive foam | Materials: Certi-PUR and Oeko-tex certified 100% polyester Cairfull® spacer fabric and individual pocket springs in high-density nursery grade foam | Size: 140cm x 70cm x 12cm or 120cm x 60cm x 12cm

Reasons to buy

  • Unique breathable fabric
  • Standard-sizes
  • Antibacterial, spill-proof cover
  • Great price
  • Long-term use from birth until age 6

Reasons to avoid

  • Not as cheap as some budget options

Our verdict

Our favourite features? Eve's cot mattress is luxuriously soft, with a unique highly breathable 2-layer material that’s water-resistant, wicks away moisture and encourages air flow to help little ones sleep soundly.

Eve's cot mattress offers a comforting mix of springs and foam in 2 sizes to give your little one the supportive, safe and clean sleep they need to rise and shine. Better yet, the waterproof layer protects them from spills, bugs, and the mattress cover is antibacterial for added reassurance. This is a superb all-rounder at a very good price. Suitable from birth until your little one(s) turn 6.

4. Best natural baby cot mattress: Naturalmat Coco Mat Organic Handmade Hypoallergenic Cot Mattress

Price on writing: £235 | Buy now from Amazon

Key specs

Type: Natural fibre mattress | Materials: Organic coconut fibres, organic lambswool and fire-safe natural fibres. The quilted cover is coated with OEKO-TEX, a certified hypo-allergenic treatment that protects against mites and bed bugs | Size: 140cm x 70cm x 10cm

Reasons to buy

  • Comfy and washable
  • Natural, anti-allergy materials
  • Made by a small business supporting local farmers in Devon and Somerset

Reasons to avoid

  • Nothing obvious, although buying a mattress cover is recommended by the manufacturer

What Mumsnet users say

“We got a lovely one from Naturalmat – it’s organic wool and handmade in Devon. It's so lovely and DS has slept so much better since he moved next to me into his cot with this. He’s 2.5 and has had it since he was about nine months and it’s still firm.” (Rated by Mumsnet user HarrietM87)

Our verdict

Our favourite features? Made from a springy coconut fibre coir, this mattress is chemical- and toxin-free, breathable, supportive and very durable, and come with a machine-washable cover that's nice and practical.

Handmade and eco-friendly, this popular Naturalmat cot mattress was the recipient of a Queen’s Award for Sustainable Development 2020, and it’s easy to see why.

The natural fibres will help to keep your baby cool on hot summer nights and cosy on chilly winter ones. Ideal for newborns but also with the firmer support required by older babies, it’ll last well, and the attention to detail here is excellent, even if it is reflected in a premium price. 

The mattress is available in around 30 sizes, with many designed specifically for popular cots such as the SnuzPod 3, the Chicco Next2Me and even unusual shapes such as the Babybay, so you can be sure you're getting the fit perfect every time. 

5. Best easy-clean cot mattress: IKEA Jättetrött Pocket Sprung Cot Mattress

Price on writing: £99 | Buy now from IKEA

Key specs

Type: Pocket sprung mattress | Materials: Pocket spring with polyurethane foam | Size: 70cm x 140cm x 11cm

Reasons to buy

  • Durable
  • Standard-sized
  • Robust construction

Reasons to avoid

  • Some reviewers clash on the issue of whether or not the Jättetrött mattress could be better ventilated, but this is a minor quibble

Our verdict

Our favourite features? The foam filling and pocket springs are designed to let air circulate throughout the mattress, preventing your baby from getting hot and sweaty in their sleep. 

IKEA’s Jättetrött Pocket Sprung Mattress is a bestseller on account of its reliable combination of quality and price. The outer cover is removable and machine-washable at 60°C – which is a major plus point among parents who’ve learned the hard way for their experience of cleaning up babies’ thrills and spills. The inner liner ensures that, when the external cover is washed, everything can be easily put back together again, and the cover simply zips off to wash with no fuss at all.

Top-rated by Which? in their latest survey of cot mattresses, this is exactly what you expect from IKEA: a nice, no-fuss product at a fair price. The only criticism we’ve heard is that the mattress costs more than the IKEA cots but, really, you get what you pay for with a mattress and it’s clear that there’s a lot more design going into this than into a flatpack wooden cot, so we think it’s fair enough. The zip-off cover is a major boon and something you should seek to replicate, whatever type of mattress you buy.

6. Best cot mattress for comfort: Mamas & Papas Baby Essential Pocket Spring Cot Mattress

Price on writing: From £77.50 | Buy now from Amazon

Key specs

Type: Pocket sprung mattress | Materials: Individual pocket springs and a fibre core lining | Size: 120cm x 60cm x 10cm

Reasons to buy

  • With 190 pocket springs encased in a layer of foam, it’s built for comfort and support
  • Hypoallergenic
  • Easy to clean

Reasons to avoid

  • You might want to add a mattress protector
  • Some reviewers say the mattress dents a little

What Mumsnet users say

“We got one from Mamas & Papas too. It wasn't the most expensive at all. He's still using it at almost four as it is a cot bed.” (Tried and tested by Mumsnet user percentageshelp)

Our verdict

Our favourite features? The cover removes for washing, though you’d probably want to add a mattress protector too, just in case. This will also make it easier to do a quick change in the night if you need to. 

Flat, firm and with a machine-washable cover, this Mamas & Papas mattress offers very high levels of comfort and support for babies and toddlers. It's been a bestseller in its various versions and comes from a brand that Mumsnetters rate highly for quality, looks and durability.

A few reviewers say that they found the mattress dented quite quickly, but this was by no means across the board, and the mattress does have crush-resistant walls which should actually help it to retain its shape. You can also flip and rotate this model to increase its longevity. Overall, this mattress is well-built, well-upholstered and, at 10cm tall, pleasingly thicker than most. It will do your baby proud right up until they make the move to their very first kids' bed.

7. Best cot mattresses for allergies: Purflo Breathable Cot Mattress

Price on writing: £189 | Buy now from Amazon

Key specs

Type: Foam mattress | Materials: Fire-retardant fabric, mesh padded coverings, moulded frames and mattress tube | Size: 140cm x 70cm x 10cm

Reasons to buy

  • Has excellent anti-allergy credentials
  • Some evidence that this product could reduce the risks associated with Sudden Infant Death Syndrome (SIDS)

Reasons to avoid

  • Expensive – three times the cost of our best budget mattress

What Mumsnet users say

“I bought a Purflo mattress and, although it was pricey, it was one of the best purchases we made. It's like a mesh stretched over a frame so you can adjust the tension and leave it a bit slack to discourage them from rolling onto their front. It's machine-washable so it's also good for avoiding respiratory problems. You can put a bowl of inhalant under it and it flows through, which is great when they've got a snuffle. It isn't like anything else out there.” (Recommended by Mumsnet user BagofHolly)

Our verdict

Our favourite features? The Purflo Cot Mattress is endorsed by Allergy UK because it minimises babies’ exposure to airborne allergens that can trigger asthma and eczema outbreaks.

This is a hollow mattress designed to be stripped down and cleaned to deny a home to mites and fungi. This mattress has also been likened to a ‘soft, breathable, hammock-like surface’ and there’s a lot to like about the thought that’s gone into the construction, design and materials.

The one thing that appears to let it down is that it can be fiddly to reassemble quickly, so you’ll likely need the additional Purflo SleepSurface to help you out, taking your investment over the £200 mark.

Despite all the good stuff, this mattress clearly isn’t for every pocket or every person, but owners claim that you get what you pay for with Purflo, and for those with babies that suffer from allergies, you might ask: ‘what price for a good night’s sleep?’

8. Best coil sprung cot mattress: Tutti Bambini Sprung Cot Mattress

Price on writing: £43 | Buy now from Amazon

Key specs

Type: Coil sprung | Materials: Superior foam, 100% polyester filling (no PVC) and breathable Just Tec fabric cover (breathable and wipe-clean) | Size: 60cm x 120cm x 10cm

Reasons to buy

  • Ticks all the boxes you’d expect from a mattress twice the price
  • Comfy and breathable
  • Compliant with British Standards for allergy prevention

Reasons to avoid 

  • It comes with a washable cover, but owners recommend buying an additional waterproof cover to extend the life of your mattress

What Mumsnet users say

“Babies should have fairly hard mattresses. I have a Tutti Bambini CoZee which I've used with both my babies - just used the original mattress with a waterproof layer on which I don't think softened it much anyway.” (Tried and tested by Mumsnet user JellyBellySmith)

Our verdict

Our favourite features? This mid-priced mattress boasts the safety, comfort and performance of a product that is typically found in the £100+ bracket. The fabric is air permeable for optimal ventilation while babies are sleeping.

Tutti Bambini is a longstanding family business with a solid reputation for quality products and personable service. A removable, washable cover makes any nighttime mishaps easy to sort out. A waterproof cover would make clean-ups even easier, however (this one is only washable), so you might want to add one. As it is though, the cover is lovely and breathable and the quilting gives a nice, soft feel. 

All the major bases are covered here in terms of comfort, posture, safety and allergy considerations. This is a great all-rounder at a value price and is especially popular for travel cots.

9. Best travel cot mattress: Mother Nurture Classic Travel Cot Mattress

Price on writing: From £22.99 | Buy now from Amazon

Key specs

Type: Foam travel cot mattress | Materials: Dent-resistant nursery foam (60% polypropylene, 40% polyester) and washable hypo-allergenic quilted cover | Size: 95cm x 65cm x 7.5cm

Reasons to buy

  • Breathable
  • Reversible
  • Washable
  • Added layer for additional comfort

Reasons to avoid

  • Reviewers report that this mattress is best laid flat if stored in the car boot, which could be an issue depending on the size of your car
  • There’s a smell from the new mattress, though it quickly dissipates

What Mumsnet users say

“Best if you get one with a waterproof protector under the machine-washable cover and over the foam pad so you still have breathability.” (Advice by Mumsnet user megdizzy)

Our verdict

Our favourite features? Mother Nurture prides itself on a commitment to using foam that's free from nasty chemicals – so-called organophosphate flame retardants. Amazon’s choice as its best travel cot mattress, this Mother Nurture product has run the gamut of over 5,000 reviews and 64 buyers’ questions, and come out on top.

Suitable for 0 to 48 months and for cots and toddler beds of various sizes, the Mother Nurture Classic Travel Cot Mattress is UK-made by a manufacturer with a 20-year track record. A few reviewers have commented that their babies markedly prefer their Mother Nurture travel cot mattress to their other sleeping arrangements at home. The overall impression is of a well-made, sturdy mattress that's firmer than what you’d typically expect within a travel cot.

10. Best cot mattress for babies and toddlers: Snüz Surface Duo Cot Bed Mattress

Snuz Surface Pro cot bed mattress

Price on writing: From £127.46 | Buy now from Amazon

Key specs

Type: Pocket sprung and foam mattress | Materials: Polyester and polyurethane | Size: 60cm x 120cm x 11cm

Reasons to buy

  • Dual sleeping surfaces designed for babies and then toddlers
  • Waterproof cover
  • Removable, washable cover

Reasons to avoid

  • Has to ‘breathe’ for a week before use

Our verdict

Our favourite features? The mattress has two different surfaces (one on either side, obviously): a slightly firmer surface for babies to give them the safe support they need, and a softer side for toddlers. To change between the two sides, you just zip off the removable cover and turn the mattress around inside it.

If some of the premium cot mattresses feel like quite the outlay for the year or two your child will use them, the Snüz Surface Duo will impress you as it’s suitable from birth up to age four. It isn’t cheap, but we were seriously impressed with the clever design at work here. 

Between the firm foam and the medium foam is a layer of supportive pocket springs. It’s the sort of construction you’d expect to see on a high-end adult mattress and customer reviews rave about the comfort.  That removable cover, by the way, is washable and also waterproof, so the mattress itself is well protected and can be kept fresh at all times. And despite being waterproof, it’s also breathable to stop your baby from getting hot and sticky at night. 

If we had one complaint it would be that this mattress is missing a spare cover, which would be handy in the event of a nighttime accident or spillage. However, you can buy a Snüz Cot Mattress Protector separately for £26.95.

Also be prepared for the fact that the mattress comes vacuum-packed and needs a week to settle and breathe before use, so don’t expect to unwrap it and have it in your baby’s cot the same night.  Another thing worth considering is whether you buy this cot mattress or pay a little more for the cot bed mattress. It all depends on what your child will be sleeping in and for how long, so this will require a bit of forward planning. If you’re using a cot bed rather than a slightly smaller cot, that might convert more easily to take your child up to four years of age when they’ll likely move into a junior or single bed. 

11. Best cot bed mattress: Silver Cross True Fit Superior Cot Bed Mattress

Silver Cross cot bed mattress

Price on writing: £99 | Buy now from Amazon

Key specs

Type: Hypoallergenic pocket sprung mattress | Materials: Polyester | Size: 70cm x 140cm x 10cm

Reasons to buy

  • Hypoallergenic
  • Dual surface for both babies and toddlers
  • Perfect fit

Reasons to avoid

  • No spare cover available
  • Fairly expensive at usual price

Our verdict

Our favourite features? Silver Cross is a much-loved brand but it’s branched out beyond its iconic prams and is now turning out equally iconic cot mattresses. 

Like the Snüz Surface Duo Cot Mattress, above, this mattress has two surfaces: the firmer baby surface and, on the other side, a softer surface for when your baby grows into a toddler. The main difference is that this mattress is a cot bed model only, which we think is a more natural fit for this type of baby-to-toddler option. It also has a waterproof cover that's removable and washable, like the Snüz - a very practical addition. 

One thing it has over the Snüz is the True Fit corners. Silver Cross mattresses are the only ones we've seen designed with perfectly square corners which fit neatly into the cot bed frame - do make triple sure of your measurements though as there’s no room for manoeuvre. It’s as comfy as you’d expect too, with 190 pocket springs between the two foam surfaces.  The Truefit Superior usually retails at almost £200 so it’s a bit pricier than the Snüz but you are getting a few more clever features. However, it’s currently less than £140 on Amazon, putting it much closer to the Snüz price, so we’d say this just pips it to the post.

How we chose our recommendations

Recommendations from real parents

Before we recommend new products, we always ask our trusted Mumsnet users, of which there are more than 7 million each month. That’s a lot of honest, impartial advice. 

Expert guidance

We always ensure our information represents the latest recommendations from experts so you can rely on it, and we research each product thoroughly to ensure it follows the latest expert advice and stands up to scrutiny. Here we consulted reputable sources such as Which?, the National Childbirth Trust, The Lullaby Trust and The Royal Hospital for Children in Glasgow.

Consumer feedback

We also scour the internet, leaving no stone unturned to check out real reviews from customers who have bought the products themselves and given both positive and negative feedback. 

Celebrated best products

Finally, we check to see which products have won industry awards and received recognition from trusted sources and feed this into our analysis too.

What’s the best type of cot mattress?

There are many types of cot and cot bed mattresses on the market, and they come with many different styles and features. Broadly speaking, here the five main types of cot mattress and cot bed mattresses:

  • Foam cot mattress – good value for money, and generally lightweight and easy to clean.
  • Coil spring cot mattress – open coil springs surrounded by foam and fillings. Tends to be sturdier than a typical foam mattress.
  • Pocket spring mattress – springs that are individually wrapped within a cloth sleeve/ Provides good support, but can be pricey.
  • Coir cot mattress – manufactured from coconut, latex and wool. Naturally firm and durable.
  • Hollow-frame (Purflo) cot mattress – advertised as fully breathable and fully washable. It’s basically a mesh cover stretched over an open frame. Expensive.

Because of the wide variety of cot mattress currently available, they also come in a wide range of prices from as little as £50 right up to several hundred

How do I choose a cot mattress? 

There are many elements to consider when choosing the best cot mattress:

Safety – what’s the safest cot mattress?

The safest cot mattress is one that’s firm with no sagging and that follows the relevant safety laws. Your chosen mattress should fit the cot snugly with no gaps for stray fingers or tiny toes to get trapped.

Truthfully, the look of a baby cot mattress should always be secondary to safety. There’s no getting around it. You might like ribbons and frou frou around your four-poster bed, but where a child sleeps should be kept simple and unfussy.

According to the National Childbirth Trust, British Safety Standards are your friend and you should specifically look for products conforming to them. Horrible as it is to even think of such a thing, these protocols are in place to reduce the number of accidental infant deaths that occur each year due to strangulation or suffocation.

It’s non-negotiable – whatever you buy, look out for the British Standards’ number on swing tickets and product specifications. Which? recommendations on this state: “All mattresses should have the BS 1877-10:2011+A1:2012 number on the labelling or instructions. It's preferable if it also carries BS 7177:1996 and BS EN 16890:2017 + A1:2021.”

Comfort and safe sleeping

‘Firm and flat’ is your mantra when it comes to cot mattresses. Both the centre and the edges should yield slightly and then spring back into shape when you apply pressure to the surface and then release it.

The general rule of thumb for safe sleeping is to always place your baby to sleep on their back – even if you own a breathable crib mattress. Though mattress manufacturers try to consider babies who roll onto their tummies during sleep, virtually all health professionals advise that back sleeping is safest.

Besides suffocation risk, some studies claim that there's an additional danger from babies breathing in more carbon dioxide than oxygen when they are not sleeping on their backs.

The mattress should also fit the cot snugly, with no gaps that your baby’s limbs could get stuck in - any gaps should be no more than 3cm. In addition, 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. 

Many mattresses have breathable covers, which helps to ensure air is flowing freely and that your baby won’t overheat. You can help keep your baby at the right temperature in the night by investing in good quality cotton bedding (baby sleeping bags are the easiest) and ensuring that they are always put on their back to sleep, with her arms free. The Lullaby Trust has good advice on safer sleep and reducing the risk of SIDS (sudden infant death syndrome). 

Durability and cleaning

Whether you’re buying a cot mattress, a travel cot mattress or a cot bed mattress, you must make sure that, as a minimum, it’s protected by a waterproof cover to help keep the mattress clean and dry.

The overwhelming testimony of Mumsnetters is that removable, washable zip-on covers are a must. Not only do they allow you to change bedding quickly when accidents occur, but they also prolong the life of your mattress.

This does make them more expensive, however, so if you’re going for a budget model and it doesn’t have a removable cover, it would be well worth buying a separate protective cover for it.

Eco-credentials

There’s no getting around it. Cot mattresses aren’t a buy for life, so lots will end up in landfill. But if you’re fully committed to a green-friendly solution, be careful to read the small print.

While producers such as The Little Green Sheep (see their Twist cot bed mattress above) are admirably transparent, the consumer organisation Which? believes that others play fast and loose with terminology. They say: "Manufacturers can use the terms ‘natural’ and ‘organic’ on products without needing any sort of certification. There are legal requirements for the labelling of organic foods, but not these products.”

Their advice, and ours, is to scrutinise the small print of product specs to ensure that materials used are truly what they purport to be.

Budget

In a sector where a mattress that broadly fulfils the same function can retail from £20 to over £250, getting what you pay for isn’t necessarily a given.

As a rough guide, foam mattresses are cheap and cheerful and not especially hardwearing, but that might be no bad thing if you’re planning to replace it when those little night accidents stop happening.

Spring-interior mattresses are mini versions of a typical adult mattresses and coir and Purflo mattresses are part of a subset of innovative, premium-priced ‘green’ products.

If you’re going for a more premium brand, you might want to think about its longevity. Some mattresses will last a child up to four years of age, such as the Snüz Surface Duo Cot Mattress and the Silver Cross True Fit Superior Cot Bed Mattress that we’ve featured in our round-up, so suddenly a slightly hefty price tag doesn’t seem so bad. 

Are secondhand cot mattresses safe?

Secondhand mattresses are best avoided – if only because the links between passed-on mattresses and cot death can neither be confirmed nor refuted. In 2002, a BBC story said that researchers at The Royal Hospital for Children in Glasgow claimed to have found a "significant” link between having a secondhand mattress and a risk of cot death. No causation was established, but it’s worth bearing in mind.

The Lullaby Trust charity, set up to provide expert advice on safer baby sleep and to raise awareness of SIDs, also cautions risk. They say: “If you’re using a secondhand mattress, make sure the mattress you choose was previously completely protected by a waterproof cover, with no rips or tears and is in good condition. The mattress should also still be firm and flat to keep your baby sleeping safely.” For little brothers and sisters moving onto an elder sibling’s mattress, make sure that you also do these checks.

You should also ensure that the mattress fits well, with no gaps between the mattress and the cot, and that the mattress itself is both clean and dry. 

What size should a cot mattress be? 

What’s important is that your mattress fits your cot snugly, with no gaps anywhere, so measure twice before you order. The standard size for a cot is 120cm x 60cm and 140cm x 70cm for a cot bed. However, some cots are now oval or even round, so if yours isn’t standard you might need to buy the mattress that's designed to go with it or get one custom-made.

What is the best thickness for a cot mattress?

For support, your choice of cot mattress should be no thinner than 8cm. However, a minimum of 10cm is what most experts, including Which?, recommend.

Travel cot mattresses tend to be much thinner - sometimes only around 5cm - but they aren’t intended for regular use. You can replace your travel cot mattress with a thicker version but do check that it fits exactly or is designed specifically for your travel cot.

Never be tempted to add a pillow or blankets to make it feel softer or thicker as this is unsafe. And if you add a thicker mattress, do check that there is still 50cm from the top of the mattress to the top of the side of the cot.

How do I test that my cot mattress is firm enough? 

It’s very important that a baby’s mattress is firm. It’s necessary for their skeletal development and also is vital in ensuring their safety while sleeping. Before you buy, search online to check the mattress hasn’t been recalled and that there are no other problems with it. When it arrives, check the following:

  • Run your hand across the top surface of the mattress. It should be completely flat, with no bumps, dips or bunched-up bits. 
  • Press with both hands on various spots on the surface of the mattress. When you remove your hands, there should be no indentation remaining. The mattress should spring back immediately. 
  • Again, using both hands, press all around the edges, checking that the edges are all strong and stable and that they don’t collapse and can’t be pushed in on themselves. Take special care to check this at the corners. 

How long does a cot mattress last?

The average lifespan of a cot mattress is anything between 0 to 48 months. After that point, it's time to move into a big kid bed. Best practice is to always buy a new cot mattress for each child.

How do I clean a cot mattress?

Your mattress should come with instructions on how to clean it, so read these carefully. Be especially careful not to shrink the cover, if it has one, as this may lead to it compressing the mattress, creating gaps around the outside. 

But essentially, if you want to give the mattress a thorough clean, first remove the cover, wash it according to the instructions and ensure it is thoroughly dry. Some mattresses can be washed themselves, but most are wipe-clean at best.

Vacuum all surfaces of the mattress, paying particular attention to anywhere dust might gather. Then wipe it all over with a damp cloth. If you have a spill to deal with, check the label to see if you can use a little laundry detergent too, then leave the mattress standing on one side to dry thoroughly - outside if possible. 

Do I need to flip my baby's cot mattress?

It’s a good idea to rotate your baby’s mattress 180 degrees every month or so, just so that it wears evenly. Most mattresses these days don’t flip.

Some have a special surface for sleeping on that might be water-repellent or hypoallergenic, for example, so that needs to stay on top. Others, such as the Snüz Surface Duo Cot Mattress and the Silver Cross True Fit Superior Cot Bed Mattress above, have a ‘baby’ side and a ‘toddler’ side with differing levels of firmness.

Either way, the care instructions that came with the mattress should tell you all you need to know. 

Do I need a mattress protector for my cot mattress?

A cot mattress protector is a very good idea, yes. If a nappy overflows in the night and wee soaks into the mattress, this can cause bacteria to develop inside. 

Some mattresses come with a removable, washable cover, which is great, but it’s still worth buying a protector to pop on as a spare, in case the cover has to be washed suddenly. A cover will also help to prevent dust mites and other allergens from building up.

Why you should trust us

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What is the best cot mattress/ cot bed mattress in the UK?

From a very wide field, we picked the Little Green Sheep Natural Twist Cot Bed Mattress as the best mattress for a baby's cot. As well as having two sides with different feels, it’s also made from natural materials that we think will give new parents peace of mind. It’s also available in an array of shapes and sizes.

The best of the rest are as follows:

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