Perhaps one of the most baffling things about buying a bed to the uninitiated is getting your head around the different sizing terms and their corresponding dimensions.
Because if you get this part wrong, then you could end up with a bed that’s too big for your room – or too small for your sleeping requirements.
Well fear not, because in this guide I’m going to explain the different US mattress sizes, dimensions, and naming conventions in a simple manner.
This should help you find the bed size that’s perfect for you.
US Mattress Sizes Explained
The first thing to note is that mattress sizes typically differ from country to county.
So to keep things simple, I’m only going to focus on US mattress and bed sizes in this guide.
And the second point is that the terms ‘bed size’ and ‘mattress size’ can be used interchangeably for the most part – although extra ornamentation can make the bed frame a different size.
So, it’s always useful to know the exact dimensions of the mattress in both inches and centimetres so that you can double check that everything is going to line up as intended.
This is particularly important when buying mattresses and bed frames separately online.
What are the Standard Mattress Sizes and Dimensions?
Here’s a handy table that compares the standard mattress sizes and dimensions for the United States.
I’ve provided more details about each type of mattress size below the chart.
|Size||Dimensions (inches)||Dimensions (cms)||Sleeps|
|Crib||27″ x 52″||68.6 cm x 132.1 cm||1 baby|
|Twin||39″ x 75″||99.06 cm x 190.5 cm||1 young teen|
|Twin XL||39″ x 80″||99.06 cm x 203.2 cm||1 teen|
|Full||54″ x 75″||137.2 cm x 190 cm||1 shorter adult|
|Queen||60″ x 80″||152.4 cm x 203.2 cm||1-2 adults|
|King||76″ x 80″||193 cm x 203.2 cm||1-2 adults|
|California King||72″ x 84″||182.9 cm x 213.4 cm||1-2 tall adults|
Mattress Sizes Compared Visually
Now, if you’re anything like me – looking at a table of numbers will make you glaze over and get all confused.
So, to help you quickly see how the different mattress lengths and widths compare visually – here’s a handy mattress size infographic that overlays the different sizes for you:
What is a Crib Mattress?
A crib – or toddler – mattress is sized to fit most standard cots in the US.
Now, you might be wondering why a crib mattress is so hard to the touch – wouldn’t it be better to have a soft mattress to increase comfort?
Well, a mattress that’s too soft or saggy can actually be dangerous.
Because babies lack the strength and mobility to move around as well as an adult.
And if you’ve ever slept on a memory foam mattress that’s too soft relative to your body weight – then you’ll know how it feels to get trapped in the material and end up with the foam mushing into your face when you’re on your front.
So if a baby were to end up on their front in a soft mattress – they could get stuck and encounter breathing difficulties.
Furthermore, babies’ bones are still developing – so they need a firmer mattress for added support (see more baby sleeping safety tips here).
What is a Twin Mattress?
A twin mattress – often called a ‘single’ in the UK – is 6 foot 3 inches long and fairly narrow.
This means that a twin mattress is typically best suited to younger teens that have not yet broken the 6 foot mark.
The slim nature of twin mattresses makes them suitable for use in smaller spaces such as guest rooms or even as part of a bunk bed.
However, if you tend to toss and turn a lot in the night and you’re on the larger side – you may find yourself at risk of rolling out of the bed.
As such, most adults will probably find a twin mattress too small and will typically need upgrading at some point during the teen years.
One good thing about twin mattresses is that they are often the least expensive of all the standard mattress types beyond the crib mattress.
What is a Twin XL Mattress?
A twin XL mattress is the same width as a twin mattress but 5 inches longer.
This means that whilst adults will still typically find them a bit too narrow – they are often favoured by college dorm rooms due to their space-saving qualities.
So if you’re a somewhat lanky student then you might be ok with a twin XL at a push!
Otherwise, a twin XL is probably best if your teen is too tall for a normal twin but you’re still working with limited room space.
What is a Full Mattress?
A full mattress is the same length as a twin mattress; so if you’re an adult above 6 foot then you’re probably going to find that your feet will either be too close to – or end up overshooting the edge – of the bed.
However, a full mattress is 15 inches wider than a twin – so you’ll have more room to move around laterally.
With that said, fitting a regular-sized couple onto a full mattress probably won’t work, since you’ll only have 27 inches of width each – which is the same as a crib mattress.
So, a full mattress is probably best suited to shorter teens and adults that are looking for a cheaper mattress – possibly for their first apartment when on a budget.
What is a Queen Mattress?
A queen mattress is the same length as a twin XL and 6 inches wider than a full mattress.
This makes the queen mattress one of the most popular sizes because it’s typically long enough for most sleepers, whilst also being wide enough to accommodate most couples – or give the single sleeper plenty of room to spread out.
Because queen mattresses are so widely purchased, you’ll have little trouble finding suitable bedding sets, headboards, benches, pillows, and other accessories to match.
What is a King Mattress?
A king mattress is the same length as a queen and a twin XL – but offers a massive 76 inches of width.
This makes a king sized mattress the best option for couples that would like the approximate width equivalent of a twin sized bed to each move around in.
That’s why some folks will push two twin XLs together to form a poor man’s king sized bed!
If you frequently have kids or pets that like to share your sleeping space – a king sized mattress could be just the job.
And if you’re a lighter sleeper with a more acrobatic bed partner then the extra space might just save you from being disturbed, especially if you’ve got a high quality foam mattress with good motion isolation – such as the Tuft and Needle range.
One thing to keep in mind when shopping for a king sized bed is making sure you’ve got enough space in your bedroom.
Also, you’ll want to make sure that you can actually get the mattress through the surrounding stairwells, door frames, and any other connecting spaces.
(Check out my mattress moving guide for some handy tips).
What is a California King Mattress?
A California king mattress is actually 4 inches narrower than a regular king – but it’s also 4 inches longer.
The California king is a great option for taller sleepers that don’t need quite as much width – which could be just the thing if you’re also working with a narrower room space.
Before I leave you, I’d like to round this post off by taking the time to answer a few common questions relating to mattress sizes.
Are Mattress and Bed Sizes the Same Thing?
Generally speaking – yes.
But you’ll need to remember that mattress sizes typically differ from country to country by numerical dimensions.
So if you’re ordering a frame and a mattress separately from different countries, then you’ll need to check the numerical measurements for each to ensure compatibility – rather than relying on naming conventions alone.
Another thing to keep in mind is that even if two mattress are the same size in terms of name – unique manufacturing styles may cause the actual dimensions to differ slightly.
For example two twin mattress from two different US manufacturers may differ in terms of how the padding is integrated and so may differ in the final size.
Additional ornamentation can also mean that the frame size is different to the actual mattress size.
Also, mattress sizes may differ from bedding sizes – including fitted sheets, flat sheets, and duvet covers.
Is a Twin Mattress the Same as a Single Mattress?
Yes – the two terms can be used interchangeably.
A single mattress is the same as a regular twin mattress.
Both measure 39″ x 75″ (so a twin XL would be longer than a single).
But why the confusion?
Well, it appears that ‘single’ is typically used more in the UK, whilst ‘twin’ is used more in the US.
I believe that a twin bed is used in the context of a matching pair of single beds – typical of what you might find in a hotel, or a bunk bed.
Is a Full Bed the Same as a Double Bed?
Yes – the difference once again is simply the naming convention.
Both a full bed from the US and a double bed from the UK or Ireland measure 54″ x 75″.
However, to avoid inaccurate generalisation – please take care to note that nominal UK and US mattress sizes are typically different.
What are the Adjustable Bed Mattress Sizes?
Typically, you’ll find that mattresses for adjustable beds follow the same naming convention as listed above.
But in addition to the regular twin, twin XL, full, queen, king, and California king sizes, you’ll also see ‘split’ sizes too – such a ‘split king’ mattress.
A split mattress is two mattresses that can be controlled independently by the adjustable base.
Now, the naming convention applies to the OVERALL size of the mattress when each mattress is combined.
So a split king mattress would actually comprise of two twin XL mattresses.
However in all cases, you’ll want to take extra care to make sure that the dimensions and the functionality of the adjustable bed base is suitable for the mattress.
What’s the Best Mattress Size to Buy?
The best mattress size is going to depend on your physical size, the constraints of your room, and your sleeping requirements – such as sleeping alone or with a partner.
One handy tip is to pick a mattress that’s around 4 – 6 inches longer than the tallest person to avoid dangling off the end of the bed.
If two people are going to sleep in the bed, one suggestion is that both people should be able to lie on their back with their hands behind their head – without their elbows touching.
Another thing to consider is the edge support of the mattress.
For example, a memory foam mattress that’s both too narrow and has poor edge support may mean that you experience the sensation of ‘falling off’ when you get too close to the edge of the bed.
Also, you’ll want to factor in things like how much room your bed partner tends to take up, if children or pets like to share your bed, and the logistics of getting the mattress into your room.
Beyond the size of the mattress, you’ll also want to think about the type of material and the structure.
So if your old spring mattress is becoming uncomfortable – possibly to the point where you’re waking up with aches and pains – then you might like to consider a foam or hybrid mattress.
Click the button below to choose from the best new mattresses to buy now.
Image Attribution and Licencing
Main image: ‘Modern Luxury Bedroom’ by Memory Catcher 168384 (Pixabay) – used with permission under Canva’s One Design Use License Agreement.
Dan is the founder and head content creator at Bedroom Style Reviews.
He has been working as a professional online product reviewer since 2015 and was inspired to start this website when he ended up sleeping on a memory foam mattress that was too soft and gave him backache.
Through in-depth research and analysis, Dan’s goal with this website is to help others avoid such pitfalls by creating the best online resource for helping you find your ideal mattress, bedding, and bedroom furniture.
Dan is a qualified NVQ Level 2 Fitness Instructor with 6 years’ experience helping clients improve their health through diet, exercise, and proper sleep hygiene.
He also holds several college and university-level qualifications in health sciences, psychology, mathematics, art, and digital media creation – which helps him to publish well researched and informative product reviews as well as articles on sleep, health, wellbeing, and home decor.
Dan also has direct personal experience with insomnia, anxiety, misophonia (hypersensitivity to sounds), and pain from both acute and long-standing sporting injuries – he enjoys writing insightful articles around these subjects to help fellow sufferers of such conditions.
Learn more about Dan here.