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What Size Is A Bunk Bed Mattress?

Bunk Bed with Mattress

Bunk beds have proven to be a popular investment for a lot of parents. Not only are bunk beds great for maximizing space, but they can also make sleeping more fun for children. So, for both parents and children alike, bunk beds are a great option. Still, purchasing a bunk bed is just the first step to outfitting a bedroom. Now, you need the appropriate mattresses for the new bunks. So, the inevitable question arises, what size mattresses do I need for a bunk bed? Believe it or not, there are so many factors to consider - mattress size, quality, durability, and of course, price point. However, in this guide, we break down the various bunk bed mattress sizes to make the mattress buying process a little easier for you.

Different Types/Sizes of Bunk Beds

It is important that you purchase the correct mattress size for your bunk bed. Because they are usually intended for use by children, bunk beds generally come with added concern for safety. Buying the incorrect mattress size can lead to:

  • A mattress that extends above the guardrails
  • A gap between the guardrails and the bedding

These are two issues that you want to avoid. To ensure you get the right mattress size, you need to pay attention to the type of bunk bed you get. The size of a bunk bed mattress is determined by the size of the bunk’s bed frames. Bunk beds come in a variety of types and sizes, but most often remain on the smaller end of the mattress size spectrum. Most bunk beds use twin size mattresses, but some are built to accommodate slightly larger sizes. Here is a summarized list of the most common bunk bed mattress sizes:

  • Twin over Twin: This is the standard bunk bed construction that fits two traditional twin size mattresses, each mattress measuring 38 inches wide and 75 inches long.
  • Twin XL over Twin XL: These mattresses measure a little longer than a standard twin size. They are 38 inches wide and 80 inches long (same length as a king or a queen size). Twin XL bunk beds are great for taller sleepers, as they provide extra legroom.
  • Full over Full: These bunk beds measure 53 inches wide and 75 inches long. Full size mattresses are the same length as twin size, but offer almost 15 inches of additional space to stretch out. Full size bunk beds are not as popular, but they are becoming more common with teens and college-aged adults.
  • Twin over Full: In this case, the top bunk would be a twin size mattress while the bottom bunk is a full size. This configuration is relatively common when children of various ages are sharing a room.

Although king or queen size bunk beds are rare, they still are available:

  • Queen size mattress: 60 inches wide and 80 inches long
  • King size mattress: 76 inches wide and 80 inches long

What to Consider When Choosing Your Bunk Mattress

It goes without saying that your main priority when selecting your bunk mattresses is most likely bunk bed safety and long term sleep quality. With this in mind, the factors you should consider when choosing your mattress include:

  • Thickness: The ideal thickness of the upper bunk mattress is 6 to 8 inches. Having a low profile mattress height is important because you want to stay within the bounds of the guardrails and make sure you still have enough headroom.
  • Weight: A lightweight mattress is preferred for the upper bunk because a heavier mattress can actually pose a safety risk. Just be sure to check the maximum weight capacity of the bunk bed.
  • Cooling Technology: Because heat rises, it can get warm in the top bunk. So, you may want to invest in a mattress with cooling technology that can help regulate body temperature throughout the night.

How Can a Bunk Bed Benefit You?

There are many advantages in purchasing a bunk bed, especially when you outfit your new setup with high-quality mattresses. BedInABox® mattresses are constructed with safe, CertiPUR-US® certified memory foams and are available in all three of the popular bunk bed sizes. While we suggest looking into our lower profile mattresses first, such as our lighter weight Essential or Original mattress models, we do have mattresses suitable for all bunk bed configurations. Some other advantages of bunk beds include:

  • Additional space: With the two beds stacked over one another, you now have free, valuable floor space. You can add more furniture and your kids can have more room to play.
  • Saving money: You don’t have to worry about the added expenses of multiple headboards and foundations/box springs.
  • Bed versatility: Bunk beds can often be separated into two beds if needed. They come in many different configurations that can include trundles, built-in drawers, or even cubbies.

Mattress Toppers for Bunk Beds

If it is not time yet for a new mattress, but your bunk bed could use a comfort upgrade, we always suggest looking into adding a mattress topper. Our toppers are designed to fine-tune your sleeping surface, adding a layer that's either softer or more supportive, depending on what you need. They're simple but effective—turning a standard mattress into something that feels a bit more tailored to you. Just as it’s important to consider bunk bed mattress height for safety measures, it is important to consider any extra height your topper may add to your current mattress.

Other Mattress Essentials for Your Bunk Bed

Complete your cozy bunk bed with our selection of bedding essentials. From blankets to sheets and protectors, we've got all the bases covered. It's about more than just bedding; it's about creating a sleep environment that is comfortable and protected.


The finishing touch to any sleep setup is the perfect pillow. Ours are crafted to cradle you into comfort, supporting your head and neck in just the right way. Whether you're a fan of memory foam's gentle embrace or prefer the classic down feel, offer a variety of options.

The Security of a USA Made Bunk Bed Mattress

BedInABox® is about more than crafting mattresses that promise a great night’s sleep. We’re about weaving safety and reliability into every stitch and seam. Our American- made mattresses stand above our competitors thanks to our commitment to not just superior comfort, but also to the well-being of your family. With our mattresses in a box, certified free from harmful chemicals and adhering to stringent safety protocols, you're not just choosing comfort—you're choosing peace of mind.

Frequently Asked Questions

What are the standard sizes for bunk bed mattresses?

Bunk beds come in a variety of sizes, with the standard size being twin (38” x 75”).

What are the safety considerations when choosing a bunk bed mattress size?

Some safety considerations when choosing a bunk bed mattress size include the width, weight, and height of the mattress. A mattress that extends over the sides of the guardrails or leaves too much space poses a significant safety risk, which is why it’s crucial to ensure that the width of the mattress fits properly within the bunk bed frame’s dimensions. Similarly, you do not want a mattress that is too heavy or too tall, as both may become a safety hazard.

Are there bunk beds that accommodate king or queen size mattresses?

There are bunk beds that accommodate king or queen size mattresses, but these are far and few between. More common bunk bed sizes include twin, twin XL and full size beds.

What should be the ideal thickness of a bunk bed mattress?

Lower profile mattresses are generally a safe choice for use with a bunk bed. The BedInABox® Essential mattress, measuring 9” in height, the Original Mattress, measuring 11” in height, or the Azul® mattress, also measuring 11” in height, are our best suggestions for bunk bed setups.

Why is the weight of the mattress important when choosing a mattress for a bunk bed?

For safety and practical reasons, the weight of the mattress is an important factor to consider when choosing a mattress for a bunk bed. Choosing a lightweight mattress in a box not only makes it easier to set up the bunk bed, but is also safer for the top bunk.

What are the benefits of having a bunk bed?

A bunk bed helps save money and space, making a bedroom more economical and practical. With two beds stacked together, you save money on headboards and foundations, and the room offers more space for furniture or play.

Why might I need a mattress with cooling technology for my bunk bed?

Since heat rises, the top bunk in particular may greatly benefit from a cooling mattress in a box, such as the BedInABox Azul®. When paired with cooling pillows and bedding that helps regulate body temperature, mattresses with cooling technology work even more effectively.

Original Product Image
11” multilayer foam construction designed with CoolRest® Gel memory foam to bring you cool, comfortable memory foam support.
Starting at $561.75 $749
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Azul® Product Image
11” medium-soft multilayer foam construction with an UltraCool® soft knit cover and our most advanced cooling system to keep you sleeping comfortably.
Starting at $674.25 $899
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Tranquillium® Product Image
12” and three layers of memory foam support infused with CoolRest® technology for those seeking maximum support and comfort.
Starting at $749.25 $999
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