What is the biggest mattress size? Stop sleeping cramped.
The Alaskan King is widely considered the biggest mattress size, measuring a massive 108 inches by 108 inches (274cm x 274cm). For UK shoppers, the Caesar mattress is the largest standard option at 8 feet wide, while the Emperor (6ft 6in) is the most common oversized luxury choice found in stores.
I once bought a Super King thinking it would solve my space issues. I was wrong. Between two growing kids and a Golden Retriever who thinks he is a human, I still ended up sleeping on the very edge of the bed. That experience started my hunt for something bigger. If you are tired of getting kicked in the ribs at 3 AM or your feet hang off the end of the bed, you need to know what is the biggest mattress size available today.
The Giants of the Mattress World
Most of us are used to the standard sizes found in local shops. But there is a whole category of oversized mattresses that make a standard King look like a cot. I didn’t even know these existed until I started looking for custom bedding. These beds are usually made to order and require a huge bedroom to look right.
The Alaskan King
This is the undisputed heavy hitter. It measures 9 feet by 9 feet. It is a perfect square. This bed is built for co-sleeping families or people who own multiple large dogs. I laughed when I first saw one because it looks like a padded room rather than a piece of furniture. You will need a bedroom that is at least 16 feet wide to fit this without feeling claustrophobic.
The Texas King
If you are exceptionally tall, this might be your best bet. It is narrower than the Alaskan but longer. It measures 80 inches wide by 98 inches long. I have a friend who is 6 foot 7 and he swears by this size because his feet finally stay warm under the covers. It fits better in narrower, longer rooms where a square bed would block the door.
The Wyoming King
Think of this as the middle ground. It is 84 inches by 84 inches. It is basically a foot wider and longer than a standard California King. It is big enough for a couple and a child to sleep comfortably without touching each other. It is also a bit easier to find sheets for compared to the Alaskan giant.
What is the Biggest Mattress Size in the UK?
UK bed sizes differ from the US. If you go into a standard high street shop, the Super King is usually the limit. However, luxury retailers and custom makers offer even bigger options. I found that while the US loves their Kings, the UK terminology gets a bit more regal.
The Emperor Mattress
The Emperor is the most common “extra large” size in the UK. It measures 200cm by 200cm (roughly 6ft 6in square). It gives you plenty of room to starfish. I found that many high-end hotels use this size to give guests a sense of luxury. It is much easier to buy a frame for this than the custom US sizes.
The Caesar Mattress
This is the true giant of the British bedroom. It measures 8 feet wide (244cm). I personally find this size a bit overkill for most UK homes. Our houses tend to have smaller rooms and narrower staircases. Trying to get a Caesar mattress up a flight of stairs is a nightmare I wouldn’t wish on anyone.
Comparing the Largest Mattress Sizes
To help you visualise how much floor space you are going to lose, here is a quick breakdown of the dimensions and who they actually serve best.
| Size Name | Dimensions (cm) | Best Use Case |
|---|---|---|
| Alaskan King | 274 x 274 | Co-sleeping with kids and pets |
| Texas King | 203 x 249 | People over 6ft 5in tall |
| Caesar (UK) | 244 x 200 | Grand, wide master bedrooms |
| Wyoming King | 213 x 213 | Large square bedrooms |
| Emperor (UK) | 200 x 200 | Standard luxury upgrade |
Mistakes I Made When Looking for a Huge Bed
I learned quickly that buying the biggest mattress size involves more than just clicking “buy” online. There are logistical hurdles that can ruin your day if you don’t plan ahead. Here are some things I overlooked at first.
The Staircase Struggle
I didn’t expect the delivery guys to look so annoyed when they saw my stairs. If you live in a house with a turn in the staircase, a solid 8-foot mattress is not going up. Many people have to order “zip and link” versions. This is basically two smaller mattresses that zip together to form one giant bed. It makes moving it much easier.
The Bedding Cost
Standard sheets from a supermarket will not fit. I had to source specific oversized bedding which costs significantly more. You also need a duvet that is even larger than the mattress so it hangs over the sides. If you buy an Alaskan King, expect to pay a premium for custom-made linens every time you want a new colour.
Room Proportions
A bed should not touch three walls of your room. I tried to squeeze a large bed into a guest room once and I couldn’t even open the wardrobe doors. You need at least two or three feet of walking space around the edges. If your room is smaller than 12 by 12 feet, stick to a Super King.
Who Should Actually Buy These?
These beds aren’t just for showing off. For some people, they are a necessity. Based on my research and speaking with others, these are the main reasons to go big.
- The Co-Sleepers: If your children often end up in your bed, a 7-foot or 8-foot wide mattress prevents everyone from waking up cranky.
- The Very Tall: A Texas King is a life-saver if you are tired of your heels hanging off the edge of the mattress.
- Couples with Different Sleep Schedules: If one of you tosses and turns, a giant bed means you won’t even feel the other person moving.
- The Pet Lovers: If you have two large dogs, they will take up 50% of a standard King. An Emperor gives everyone their own zone.
Frequently Asked Questions (FAQs)
What is the biggest mattress size in the world?
The Alaskan King is generally the largest standard oversized mattress at 108 by 108 inches. However, some custom manufacturers can create even larger “Family Beds” that reach up to 12 or 14 feet wide for specific needs.
Can I use two mattresses to make a giant bed?
Yes, this is common. Putting two Double mattresses together makes a bed that is roughly 9 feet wide. Using “zip and link” sets is better because it prevents a gap from forming in the middle where you might fall through.
Where do you buy sheets for an Alaskan King?
You won’t find them in standard shops. You usually have to buy them from specialist online retailers or the company that sold you the mattress. Some people also have them custom-sewn from larger rolls of fabric.
Will a giant mattress fit through a standard door?
Usually, no. Standard internal doors are around 30 inches wide. A solid giant mattress will not fit unless it is a “bed in a box” that expands once it is inside the room or a split-base model.
Is it hard to find a bed frame for an Emperor size?
It is easier than it used to be. Many luxury bed brands in the UK now offer Emperor frames as a standard option, though you will likely have to wait longer for delivery compared to a Double or King.
Final Thoughts on Choosing a Large Bed
Upgrading to a larger bed changed how I sleep. No more waking up because someone shifted an inch to the left. While the Alaskan King is the record holder, most people find that a UK Emperor or a Wyoming King offers the best balance of luxury and practicality. Just remember to measure your hallways and doors before you commit to anything. Taking the time to figure out what is the biggest mattress size that fits your home ensures everyone gets a decent night of sleep.
I’m Derek Sutter, and I test sleep products for Bed Sleep Advisor from my home in Wyoming Ranchettes. Over the past 9 years, I’ve reviewed 60+ mattresses, everything from budget foam to premium hybrids, tracking firmness, motion isolation, and heat retention myself. Before this, I spent six years in furniture retail, where I watched customer after customer get overwhelmed by mattress shopping. That’s what I focus on now: real durability and comfort, not spec sheets.
