The Complete Mattress Buying Guide

There are a lot of factors to consider when choosing the right mattress for babies, toddlers and adults, and it's certainly not one size fits all!

The most important things to keep in mind are the type of mattress, the materials such as innerspring or memory foam and the firmness, which is important for support and comfort.


You also need to make sure that you think about the size. Mattresses come in a huge range of sizes suitable for different sleeping setups.

For example, a crib mattress should be smaller than a twin mattress. A twin mattress should be smaller than a full mattress. A full mattress should be smaller than a queen mattress. And so on.

It's worth mentioning, too, that Moses basket mattresses are a lot smaller and lighter than regular crib mattresses. These should ideally be purchased with the Moses basket.

So, with the basics out the way, let's dive into more detail in our guide to help you choose the perfect mattress for your baby, toddler or for yourself!

A Mini-Guide to Mattress Sizes

When it comes to purchasing a mattress, you need to make sure that it is going to fit properly. An ill-fitting mattress can be uncomfortable and annoying for adults and hazardous for children.

For example, your child can get their limbs caught in the gap between the mattress and the bed, which is why you need to ensure that there is no more than a centimetre gap.

In addition to considering the width and length of the mattress, you should also consider the depth too. Most of the time, the manufacturer of the cot, crib, bed or whatever piece of furniture you are looking for a mattress for, should have a user guide including recommended mattress sizes to make it easier for you to find compatible mattresses.

  • Always read the user guide or instructions
  • Measure properly
  • Remember to consider the depth

Getting the fit right is important because it speaks directly to you or your child's comfort and safety, so it is essential that you get it right.


Mattress Size Guide

Most of the time, mattresses come in standard sizes, as outlined in the table below. This means that most cribs, cots, et cetera are designed for one of the below sizes to fit.

Luckily, the user guide will often tell you what size mattress you are looking for, which will make things easier for you.

Mattress SizeDimensions (Length x Width)
Moses Basket60-90cm x 28-50cm
Crib70-90cm x 35-50cm
Carrycot / Pram65-85cm x 30-35cm
Cot 120-140cm x 60-80cm
Cot Bed120-140cm x 60-80cm
Small Single190cm x 75cm
Single190cm x 90cm
Double190cm x 140cm
Queen200cm x 150cm
King200cm x 180cm
Super King200cm x 200cm

Please note these are standard sizes, and you should measure your bed prior to purchasing a mattress.

How to Measure Up for A Mattress

When it comes to measuring your furniture for a mattress, it is actually pretty simple. First things first, if you still have the packaging or instructions from your bed or your child's cot or crib, it should tell you in there what size mattress you need to buy.

If you do not have it, or it doesn't tell you, then you simply need to take three measurements. You want to measure the width, length and height of the interior of the crib or bed. This should give you the measurements that you need to purchase the right size.

Buying Made-to-Order Mattresses

Sometimes, you will find that the bed, cot or crib that you have ordered is a little unique. It might be vintage, custom, or simply unusual. If this is the case, you are likely to find that the standard mattress sizes won't work.


This will mean that you will need to purchase a custom-made mattress. The The Little Green Sheep offer this services and the process of ordering is pretty straightforward. You simply provide the measurements, and we do the rest.

Mattress Materials

After you have an idea of the size that you need, the next thing to think about is what material you want for the mattress you are buying.

Again, there are several mattress materials to choose from, all of which have their own merits and drawbacks.

Each mattress offers different levels of support for the body, which is something that you should consider. This is directly linked to the materials, so let's break down your options.


Organic or natural mattresses are firmer than other options and designed to provide maximum support. Their biggest draw is that they are made without synthetic chemicals, which makes them more fire retardant and breathable. However, they can be a little more expensive.

Organic Mattress Materials

Organic mattresses can come in several different materials depending on where you plan to buy them from. There are some materials that you are more likely to encounter and some that are unique to certain manufacturers, like the ones below, which make up The Little Green Sheep's organic mattress.



Cotton is super soft on your baby's skin which can reduce the chance of any skin irritation. It also tends to add to the breathability of the mattress too, which can help to ensure that your baby doesn't get too hot or too cold


Wool is actually a naturally hypoallergenic material. It, like cotton, is also more breathable and able to regulate its own temperature, which keeps your baby more comfortable. And also, like cotton, it is naturally fire retardant too.

Coconut Fibres

Coconut fibres are taken from the husk of coconuts and used to form the inner core of the mattress. The fibres act as springs and can help reduce pressure points and provide even more support throughout the mattress.

Natural Latex/Plant-Based Foam

Natural latex is made from the sap excreted by the Hevea tree. It is used as a substitute for the glue to bind the coconut fibres together. It can also act as a layer of foam to provide more comfort.

Memory Foam

Memory foam mattresses are made from a type of foam that is very dense and firm but also very soft and comfortable. The foam contours to the body, providing support and relieving pressure points and a great deal of support, making them perfect for people who suffer from back pain or other types of pain.

You can buy memory foam mattresses for adults and children. They are available in various sizes, including twin, full, queen and king. You can also find memory foam mattresses made specifically for people who suffer from allergies or have other sensitivities.


An innerspring mattress consists of internal springs coupled with an extra layer of foam on top to make the comfort more consistently spread throughout the mattress. They are one of the older mattress designs, often being a little cheaper and providing average support.

Pocket Spring

A pocket spring mattress is exactly as it sounds. The springs are housed in individual pockets throughout the mattress. This means that the springs work independently of each other, providing support where needed.



A hybrid mattress, as you can probably guess, combines elements of the other mattresses listed above. They usually have several layers consisting of springs, foam and latex. They can be a great compromise for those who can't decide, offering the best of both worlds in a way.

Soft vs Firm Mattresses

The next thing to consider after having been through the size guide and materials is the firmness of the mattress.

The materials that you have chosen can directly impact the firmness of the mattress, which is something that you need to think about. The scale ranges from extra soft through to extra firm.

Different levels of firmness are suited to different ends. Unfortunately, there is no exact science to determine which firmness you should choose because it comes down to personal preference.

That being said, some general rules can help you work out which would work the best for you.

Soft Mattresses

A soft mattress allows the body to sink in and be nestled by it, which can be desirable for those seeking extra comfort. In addition, they are said to be great for those who sleep on their side or lighter sleepers because a firm mattress can be more unforgiving and keep them awake.

In terms of support, soft mattresses tend to have less support than firmer mattresses which is something to think about.

When it comes to which is better for back, muscle or alignment problems, there are opposing schools of thought, with some saying soft is better and some saying firm. If possible, you should give both a try in person before committing.


Firm Mattresses

Firm mattresses are designed to prevent the body from sinking into the mattress. Often, this means that a firm mattress tends to be more robust, increasing its longevity, meaning that it will last longer.

A firm mattress can also be used with a softer mattress topper which can provide you with more options for its use. As mentioned above, there are those that believe that a firmer mattress reduces pressure on the circulatory system and encourages the body to align properly.

Mattress Weight

Mattresses can vary dramatically in weight depending on the materials used and, of course, the size of the mattress too. Smaller mattresses are going to weigh less than bigger mattresses. Baby mattresses are obviously incredibly lightweight, and king mattresses are the biggest and therefore the heaviest.

Memory foam and innerspring mattresses tend to weigh the least, being less dense than other materials. Hybrid mattresses are next, and they do range in weight, then latex mattresses which tend to be the heaviest.

Baby Mattresses

As a first-time parent, it can be a little daunting when it comes to choosing a mattress for your baby. With so much advice out there, it can be hard to work out which option is the best for your baby.


There are several options when it comes to baby mattresses and it depends entirely on what you have for your baby to sleep in. There are cots, cribs and Moses basket mattresses. They can vary as much in material as adult mattresses.

Cot & Crib Mattresses

A cot or crib tends to be made from sturdier materials like wood or plastic. They are less portable but often can be used for longer in your baby's life than a Moses basket. They also often come flat packed, having to be built.

You need to ensure a snug fit when buying a mattress for your baby's cot or crib. The gap between the mattress and the cot or crib should be less than a centimetre to ensure that your baby cannot trap their limbs and hurt themselves.

Realistically, the manufacturer of your cot should have provided a user guide detailing the size of the mattress you should buy.

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Natural Crib Mattresses

From £69.95

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Natural Cot Mattresses

From £179.95

Moses Basket Mattresses

Moses baskets are more geared towards newborns and babies in the first few months of their lives. Often seen as a more traditional choice, the use of Moses baskets dates back centuries. They are smaller and portable, which can be a big draw for a lot of parents.


Some Moses baskets are sold with a mattress, but this is not always the case. If your Moses basket and mattress are to be sold separately, it is worth purchasing them from the same retailer to ensure that they will be size compatible. If in doubt, check the dimensions.

Toddler Mattresses

A toddler bed is a stepping stone between a crib and an adult bed. It is often seen as a milestone in your toddler's life, and it is important to get the transition right. This means providing support and nurturing your child's physical and psychological needs as they make the change.

The first thing to consider when purchasing a toddler mattress is the size. Again, it is imperative that it fits properly to reduce the risk of entrapment and suffocation. In addition, toddlers tend to need firmer mattresses to provide their bodies with support and aid in proper alignment.

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Natural Moses Basket Mattress

From £59.95

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Natural Single/Child Mattress

From £345.95

Adult Mattresses

Choosing a mattress for yourself as an adult will depend on several factors. Things like your weight, height, build, age and preferred sleeping position can affect what type of mattress you find more comfortable and are more suited to.


You need to find a mattress that provides the support that you need. As mentioned above, mattresses vary dramatically in firmness, affecting the support they provide. The scale ranges from extra-soft, soft, medium-soft, medium, medium-firm, firm and extra-firm. Do your research and try some out if possible to work out which one is the best choice for you and your body.

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Natural Adult Mattress - Double 


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Natural Adult Mattress - Single 


Mattress Covers & Protectors

Some people think that a mattress protector is a waste of money, but this couldn't be further from the truth. Mattress protectors should always be used; they help to make your mattress last longer by keeping them clean and preventing stains and damage. 

Mattress protectors can also provide an additional barrier between you and the mattress, which can help those with dust-mite allergies or skin irritations. A mattress protector can also help to protect your warranty too.

Mattress Safety Standards

It is vital that you ensure that any mattress that you buy for your or your family adhere to the safety standards set in place by the applicable governing body. For example, British Standards set out a number of rules to ensure that the mattresses that you buy are of the best possible quality to ensure your health and safety are protected.

The safety standards speak to the flammability of the product, the cleanliness of the facility and materials used and their chemical composition of them. Cot mattresses are subject to more stringent safety standards too. Products that do adhere to the standards usually have the initials BS or BS EN on their labels.

SIDS (Sudden Infant Death Syndrome)

SIDs, which is sometimes also referred to as cot death, is the term used to describe the sudden, unexplained and unexpected death of an otherwise healthy baby. It is a rare phenomenon, but important to be aware of. This is not meant to instil fear because the risk to your baby is incredibly low. Most cases occur before the baby is six months old. It usually happens while the baby is sleeping – hence 'cot death'.

Although parents can reduce the risk by ensuring that their baby always sleeps on their back, you also need to be mindful of what you are putting in the crib with your baby; loose bedding and toys can also contribute.


How To Carry Out Mattress Care

Most people only swap out their mattresses every ten years, with some keeping them a lot longer than that. So in order to ensure that your mattress will stand the test of time, you need to do everything you can to take care of it.

Luckily, taking care of your mattress is pretty straightforward. First things first, you should always use a mattress protector and change your sheets regularly. Your mattress will also need to be rotated regularly to avoid lumps or sagging.

Some people also recommend hoovering your mattress four times a year using a low suction setting. This helps to pull out the dust particles and skin cells to keep your mattress clean and alleviate the possibility of skin irritation or skin allergies.

Finally, if you are unfortunate enough to stain your mattress or spill something on it, you can clean it off, but it is a process. Ideally, you should blot as much as possible before it can seep in.

After that, you should make up a solution of white vinegar and water. Gently scrub the stain without saturating the mattress. Use a clean cloth to clean out the solution and leave it to air dry before redressing the bed.


Mattress Disposal

Replacing your mattress is a process in and of itself; however, one thing that a lot of people forget to take into consideration is how they are going to get rid of their old one.

You have several options when it comes to mattress disposal:

  • Collection by the company while delivering your new one
  • Collection by the local council
  • Giving away to charity/friends/family
  • Taking to the tip
  • Recycling centres

In some instances, you will have to pay a little more to have your old mattress taken away. The other options, while free, often require a vehicle. It comes down to what option is the most convenient for you.

Final Thoughts

Adults spend around a third of their lives sleeping. Children sleep for around half of the day, and infants even more than that, clocking around sixteen hours a day of sleep. This is why choosing the right mattress is so important. The amount of sleep you get and the quality of said sleep has a knock-on effect on the rest of your daily lives.

Everyone has different needs when it comes to a mattress. Think about the factors mentioned above to work out what type of mattress best addresses your needs.


Which type of mattress is best?

This depends entirely on you. For example, your age, weight, height, build and preferred sleeping position can affect the type of mattress you should buy. Do some research to work out what type will be the best for you.

What thickness of mattress is good?

Again, this depends entirely on you. Thinner mattresses tend to be better for slimmer people and vice versa. In terms of baby mattresses, the user guide for your baby's cot or crib will recommend a thickness.

Can mattresses be washed?

Mattresses can be cleaned. The process involves a cleaning solution, scrubbing the mattresses, 'rinsing' with a clean cloth and allowing the mattress to air dry. Try to avoid saturating the mattress if possible.

Are cot mattresses breathable?

It depends on the type of cot mattress; some are, some aren't.

Are crib mattresses waterproof?

This, again, depends on the type of mattress. However, even if the crib mattress isn't waterproof, you can purchase a waterproof mattress protector.

Can baby mattresses be reused?

You can reuse a baby mattress as long as you deem it to be clean, safe and in a suitable condition to do so.