Choosing the right mattress size may seem simple, but it's actually quite complex.

Opportunities to buy bedding and mattresses are rare in life, and there are so many different sizes to choose from that it can be difficult to choose the best one for your size and situation. However, choosing a size without thinking can lead to regret later on, or you may have to replace your mattress more frequently, so choosing the right size is extremely important when it comes to mattresses.

The standards for Japanese mattresses are set by the Japanese national standard, the JIS standard, so on this page we will use that as a basis to provide a professional explanation of the main size standards, who each size is best suited for, how to choose the right size for your room, and points to bear in mind.

[Author introduction]

Senior Sleep Health Instructor (No. 733). An expert on mattresses and sleep. Purchases and tries out over 50 mattresses in a year. Helps many people choose bedding and mattresses from the perspective of sleep quality and interior design. → Good Sleep Hacks

There are seven main mattress sizes:

• Semi-single
• single
• Semi-double
• double
• Wide double
• Queen
• King

Bed and mattress sizes are determined based on the JIS standard established by the Japanese Standards Association. Mattress sizes based on the JIS standard are listed in the table below.

Not all manufacturers carry every size of mattress. It is important to note that many manufacturers do not carry larger sizes than wide double mattresses.

It is generally said that the mattress size needed for a comfortable sleep is the width of your body plus 30cm. In other words, the optimal mattress size varies depending on your individual physique, so it is important to check in advance.

From here, we will introduce the features of each mattress size and recommended situations.

Semi-single mattresses are the most compact size of all mattresses. Most are 80-90cm wide, so they won't feel cramped even when placed in a small room.

For children and small people, a compact semi-single bed is comfortable enough.

Its compact size makes it easy for women to carry around, and it's also convenient for changing sheets and cleaning under the mattress.

However, it is about 16 cm narrower than a single size, so many people find it narrower than they expected. When turning over in bed, you need to be careful not to fall off the mattress.

Therefore, if you have the space, we recommend a single or semi-double size bed, as you will be able to sleep more comfortably.

Single beds are the most common bed size. Following the semi-single bed, single beds are also very popular among people living alone due to their compact size .

If you place it in a 6-tatami room, it will take up about 1/4 to 1/3 of the room. If you have a standard body type, sleeping in the middle will leave about 25cm of space on either side, allowing you to turn over without any problems.

Also, if you connect two single-size mattresses together, it will be larger than a king-size bed. Compared to using one large mattress, you will not be bothered by the person next to you tossing and turning, so it is recommended that couples use one each, or that you purchase one for siblings.

Unlike double and queen sizes, the beds can be separated when you want to have more space for one person. This makes it convenient for couples to use the beds independently when they have their own bedrooms.

The name "semi-double" may lead you to believe it's for two people, but it's actually a single-size bed. It's more spacious than a single size, so it's recommended for larger people or those who sleep in awkward positions.

It is about 120cm wide, so even if the man sleeps in the middle, there will be at least 30cm of space on either side. It is a little narrow, but in some cases it can be used by two people.

It's spacious enough for babies and toddlers to sleep together, so if you have a family of four, two semi-double beds, or one semi-double and one double, placed side by side, would be perfect. However, since the bed is designed to withstand the weight of one person, it is not recommended for long-term use by two adults.

Also, since it is about 20cm wider than a single mattress, it is not suitable for small rooms as it creates a feeling of oppression overall.

Double beds are generally used for two people, but they are also recommended for larger people who want to sleep comfortably alone. At around 140cm wide, there is ample space to turn over in your sleep, making for an environment that is conducive to better quality sleep.

Of course, it can be used for two people, but it is surprisingly compact, being about 20-25cm narrower than two semi-single beds pushed together. Since you'll be sleeping very close together, it's not the best size for those who want to sleep comfortably.

Also, if two large people sleep together, it can feel quite cramped. They can't turn over freely, which can lead to poor quality sleep and pain from pressure on certain parts of their body.

A wide double bed is about 150cm wide, which is slightly larger than a double bed, so it is recommended for those who want to sleep comfortably with two people. If you have the space in your room, a wide double bed will be more comfortable than a double bed.

It is also cheaper than a queen size mattress, so it is recommended for those who want a larger mattress but want to keep costs as low as possible.

However, because wide double beds are a rare size, there are few manufacturers that carry them, which is a drawback. The bedding that is compatible with them, such as sheets, bed frames, and mattress covers, is also limited.

A queen-size bed is about 160cm wide and has a mattress that is twice the size of a semi-single bed and about 1.5 times the size of a single bed. Two adults can sleep comfortably.

It can also accommodate up to three small children, but it does require some space as it is quite wide.

Generally, a mattress can be placed in a bedroom of about 8 tatami mats in size, but if you live in an apartment or condominium, you will need to check the width of doors, hallways, and elevators to see if you can bring in a mattress.

Recently, many places have started to deliver in compressed packaging, making it easier to transport, but if you are thinking about moving, we recommend connecting two semi-single beds (or choosing a queen size bed that can be divided into two ).

One advantage of connected mattresses is that vibrations are less likely to be transmitted between the two, reducing the risk of waking up your partner.

However, the disadvantage is that the divided part can make it easier for your sleeping position to be disrupted. When you turn over in the center, your body can sink in too much, or the mattress can shift and create a gap.

King size is the largest mattress size, with a width of around 180cm, which is just under twice the width of a single size. Even larger king size mattresses, exceeding 200cm, are sometimes called "wide king size."

They are characterized by their large size, allowing multiple people to sleep comfortably. However, one drawback to their size is that king-size mattresses are often not able to be brought into apartment buildings in Japan.

Also, because king-size beds are rare, bedding items such as bed frames and sheets are limited. Each item is expensive, so it's difficult to replace them easily, which is another disadvantage.

From here on, we will introduce the appropriate mattress size for each room size. Use this as a reference if you want the largest mattress possible but are not sure if it will fit in your room.

[Top left] Semi-single bed, width 82cm x length 195cm
[Top right] Single: Width 98cm x Length 195cm
[Bottom left] Semi-double bed: 120cm wide x 195cm long
[Bottom right] Double: Width 140cm x Length 195cm

The size of a 4-tatami mat bedroom is 6.48 m². It depends on the shape of the room, but if it's square, each side of the room will be 255 cm. Considering the ease of opening and closing doors and the space required to move around, we recommend a mattress ranging from a semi-single to a double bed for a 4-tatami mat bedroom.

A semi-double size would still have room, but if you put a double bed in it, the bedroom will be almost full. You'll probably have enough space to put a compact nightstand. If you want to put a desk or sofa in it, we recommend a size smaller than a semi-double.

[Top left] Single bed: Width 98cm x Length 195cm
[Top right] Semi-double bed: 120cm wide x 195cm long
[Bottom left] Double bed: 140cm wide x 195cm long
[Bottom right] Wide double: Width 152cm x Length 195cm

A 6-tatami room has an area of approximately 9.7 m2. 6-tatami rooms are generally rectangular, measuring approximately 348 x 261 cm. Even if you place a double-sized mattress in a room this large, it won't feel too cramped.

In addition to the mattress, you can also place a nightstand or a small sofa. A queen size bed will be just about the limit, but if you don't have any other furniture, it can still be used as a bedroom. If you want more space, a wide double bed is appropriate.

[Top left] Single bed: Width 98cm x Length 195cm
[Top right] Double room: Width 140cm x Length 195cm
[Bottom left] Queen size 160cm wide x 195cm long
[Bottom right] King size 180cm wide x 195cm long

An 8-tatami mat bedroom has an area of approximately 12.96 square meters. If the room is square, each side is about 3.6 meters. This means that you can easily fit a double, queen, or king size bed in it.

Even if you place a king-size mattress in the center, there will still be space to place nightstands on either side. You can also place other storage furniture, so you can enjoy a variety of layouts. However, even if the room is large enough, it may not be possible to bring it through the door. Make sure you check in what condition the mattress will be brought in and make sure you have an entrance for it.

Mattresses come in a variety of sizes, so many people are unsure which size to choose. When choosing a mattress size, be sure to pay attention to the following points.

• Long size is recommended for tall people
• Floor-standing mattresses are not thick, so be careful of the feeling of hitting the bottom.
• "Connecting" to increase size is prone to misalignment
• Make space around the mattress
• Choose a bed frame that matches your mattress size

Here we will explain each point in detail.

The sizes of semi-single, single, semi-double, double, wide double, queen, and king are determined by the width. Regardless of the size, the length is generally 195 cm.

However, there are also "long size" mattresses available, which are longer in length. Long size mattresses are approximately 205-215cm in length. They are about 20-25cm longer than regular mattresses.

Long size mattresses are recommended for people who are 180cm or taller. Depending on your sleeping position and the size of your room, if you are 180cm or taller, you may want to consider a long size mattress.

In addition to the long size, there is also a short size mattress, which is approximately 180cm long. It is 15cm shorter than a regular mattress, so it can be placed compactly even in a one-room apartment.

The short size is recommended for children and petite people under 160cm tall. People over 160cm will find it too cramped, so it is safer for people between 160cm and 180cm to use an average size mattress.

If you place your mattress directly on the floor without using a bed frame, you must also be careful about its thickness. A thin mattress will make you feel the bottom of the mattress and will be more likely to feel the hardness and coldness of the floor.

Not only will it be uncomfortable to sleep on, but poor sleeping posture can also cause back pain and stiff shoulders. It is recommended to choose a mattress that is at least 8cm thick.

However, placing it on the floor tends to trap moisture, and the thicker it is, the more likely it is to become a source of mold and dust mites.

Also, thick mattresses are heavy, so maintenance is also a lot of work. It's best to lean it against a wall frequently to allow for ventilation, and it's best to choose a mattress that's between 8cm and 15cm thick. Be sure to choose a mattress with the right thickness to avoid feeling like you're hitting the bottom of the mattress.

Some people connect semi-single or single size mattresses to create a queen or king size mattress. By connecting them, the vibrations of the person next to you are less likely to be transmitted, allowing both of you to sleep comfortably.

However, because each mattress is independent, there is a disadvantage that if weight is placed on the center, they may shift and create gaps. A "mattress fixing belt" is effective in preventing the two mattresses from shifting. Use the band by wrapping it around the side of the mattress.

There are also gap pads available for sale to fill gaps. There are also washable gap pads, so they are hygienic. Be careful, as gap pads can easily become misaligned if the mattresses are different thicknesses or sizes.

If you place a mattress in the entire bedroom, it will be difficult to move around and make the bed. You should be especially careful about the space if you plan to place other furniture in addition to the mattress.

First, make sure you leave about 10cm of space between your bed and the wall so you can make it. You should also leave about 30-40cm of space on the other side so you can change your sheets.

Also, if you need to walk around the bed, the aisle width must be at least 50cm.

Next, if you have a closet or storage bed with drawers, make sure you leave about 90cm of space between the bed and the door so you can open and close it and take things in and out. If there isn't enough space, it will be difficult to take things in and out smoothly, which can be stressful.

Furthermore, if you are placing a dresser or chest of drawers, you will need to leave enough space for people to bend over in addition to being able to take them in and out. If there is a space of at least 75cm between the bed and the dresser or chest of drawers, you will be able to take them in and out easily.

The last option is to place a desk. Since you will need to pull out a chair before sitting down, you will need about 70cm of space. However, with only 70cm of space, the bed will be directly behind the chair, making it impossible for people to pass through. If you want to leave an aisle, you will need about 110cm of space.

When choosing a bed set, it is common to choose the mattress before the bed frame. First, choose a mattress size that suits your family size and body type, and then look for a bed frame that matches it.

When choosing a bed frame, you should pay attention to the following points in addition to the size:

• Design and color
• material
• Floorboards

There are various types of bed frames, including low types that are close to the ground, types with storage space under the bed, and cabinet types with lighting and shelves on the headboard. Please note that some designs may not fit the mattress size, and that taller beds such as loft beds and bunk beds have weight restrictions.

The next point is the material of the bed frame. In addition to wood, there are fabric frames covered with cloth, luxurious leather frames, and lightweight and inexpensive pipe frames. Choosing a material that matches the atmosphere of the interior will allow the bed to blend in with the room and improve the quality of life and satisfaction.

Finally, there is the floorboard, which is the part that goes under the mattress and can be either "slatted" or "planked." Mattresses tend to accumulate moisture, so a slatted floorboard is recommended to allow moisture to escape. Planked floorboards are warmer because they do not allow cold air to get in, but they require regular maintenance to allow moisture to escape.

We've explained the specific dimensions of mattress sizes and how to choose them. Mattresses sold in Japan are sized according to the JIS standard. There are seven sizes: semi-single, single, semi-double, double, wide double, queen, and king. Each size has its advantages and disadvantages, so be aware of them.

Choosing the right mattress size to suit your room size, physique, and family composition will create the best bedroom for you. Mattress size also affects the quality of your sleep, so we recommend choosing carefully.

In addition to size, compare and consider materials, designs, and bed frames to create a comfortable sleeping environment.