Bunk Bed Mattress Sizes: What Size Is A Bunk Bed Mattress?

Bunk bed mattresses can come in a variety of sizes, but twin and twin XL are most common. Twin mattresses are 38” x 75”, while twin XL mattresses are 38” x 80”.

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Bunk beds are the perfect solution for kid and adult problems alike — parents save space while children enjoy the fun of an elevated bed. Plus, who doesn’t love a never-ending sleepover?

The bunk bed, however, is only one part of the equation. The mattress is the other component.

So, what size is a bunk bed mattress? Put simply, it depends on the bed.

Our innovative  mattresses are made from multiple layers of cooling foam. Then they’re squeezed down into a tiny box, which magically appears on your doorstep within a few days.

Bunk Bed Mattresses Size Chart

When selecting the right mattress for your bunk bed, it's crucial to ensure it fits the bed frame securely for comfort and safety. Below is a quick reference chart of common bunk bed mattress sizes and their dimensions:

 

 

Always measure the inside dimensions of your bunk bed frame before purchasing a mattress to ensure a proper fit, as an incorrectly sized mattress can pose a safety risk.

Different Types of Bunk Bed Configurations

Bunk beds are generally designed for children, so the range of bunk mattress sizes is typically limited to the smaller end of the spectrum. Most bunk beds use twin mattresses, but they’re not the only kind available, with larger bunk bed sizes becoming more popular:

• Two twins – A standard bunk bed will fit two twin mattresses, each measuring 38 inches wide and 75 inches long.
• Two twin XLs – Some bunk beds are specifically designed to fit twin XL mattresses, which have the same width as a standard twin mattress but five additional inches of length — 38 inches by 80 inches — making them as long as a king or queen size bed. When comparing a twin vs twin xl mattress, twin xl mattresses are usually the better option for taller people.
• Two fulls – Full size bunk beds are less popular than the other two, but are becoming increasingly common for teenagers and even college students sharing a room. Full mattresses measure 53 inches by 75 inches. If you compare a full vs twin, they’re the same length but a full has an extra 15 inches of room side-to-side.
• One twin, one full – This is another fairly common configuration, especially for children of various ages sharing a room. The upper bunk is a twin, while the lower bunk is a full. This gives more room to the sleeper below (or some extra space for parents to cuddle up next to their kiddo for a bedtime story).
• One twin, one queen – This configuration is perfect for mixed-use rooms or situations where space and versatility are key. With a twin mattress on the top bunk and a queen mattress on the bottom, this setup is ideal for siblings of different ages or even for hosting guests. The twin mattress provides a cozy sleeping spot for a child, while the queen mattress offers extra room for a parent, older sibling, or even two sleepers.
• Two queens – Though less common, bunk beds designed to hold two queen mattresses cater to adults, larger families, or shared accommodations like vacation homes. With each mattress measuring 60 inches wide and 80 inches long, this configuration offers generous sleeping space for each occupant, making it ideal for situations where comfort and roominess are a priority.
• One twin, one king – This unique bunk bed configuration combines a twin mattress on the top bunk with a king mattress on the bottom, offering a practical solution for families or shared spaces. The twin mattress provides a cozy sleeping spot for a child or lighter sleeper, while the king mattress below delivers ultimate comfort and roominess, accommodating two adults or even multiple kids during a sleepover.
• Two kings – The two-king bunk bed is the epitome of luxury and functionality, designed for larger families, group accommodations, or shared spaces that prioritize comfort. Each level supports a king mattress, offering ample sleeping space for two adults per bunk. This uncommon configuration is also the most expensive by far.

As you can see, just about any mattress configuration exists for bunk beds, but keep in mind that more uncommon setups may come with higher price tags and limited availability, so it’s worth planning your search accordingly.

If you’re not sure of your bunk bed’s size, measure the inside dimensions before you start mattress shopping. Buying the wrong size could actually be a safety concern if it hangs over the guard rail.

Different Types of Bunk Bed Frame Styles

Now that we’ve covered the most common bunk bed configurations, let’s explore popular bunk bed frame styles. The design of the frame not only influences the look of the room but also how functional the bed will be for your needs. Here are some of the most common bunk bed frame styles:

• Standard Bunk Beds: The classic design features two stacked beds, typically with the same mattress size. This style maximizes vertical space and is a great choice for shared bedrooms or smaller spaces.
• Trundle Bunk Beds: These versatile frames include a pull-out trundle bed beneath the lower bunk, adding a third sleeping space. Perfect for sleepovers or guest accommodations, trundle bunk beds offer extra functionality without taking up additional room.
• Loft Bunk Beds: Loft beds are essentially a single top bunk with open space underneath, allowing room for a desk, futon, or storage. Ideal for maximizing floor space, they’re popular for small bedrooms or multipurpose rooms.
• Futon Bunk Beds: A futon bunk bed combines a traditional top bunk with a futon on the bottom that can double as a couch during the day. This design is perfect for multifunctional spaces, such as a teen’s bedroom or a studio apartment.
• L-Shaped Bunk Beds: L-shaped bunk beds are configured at a 90-degree angle, creating a more spacious feel and additional floor space underneath one of the beds. These are great for larger rooms and can often incorporate built-in storage or shelves for added convenience.
• Triple Bunk Beds: For ultimate space-saving, triple bunk beds stack three beds vertically or configure them in an L-shaped design. These are ideal for large families, vacation homes, or shared rooms where multiple sleeping spaces are needed. Some triple bunk beds also include trundles for even more flexibility.

Each of these styles offers its own set of benefits, so consider your room size, storage needs, and aesthetic preferences when choosing the perfect bunk bed frame.

Choosing the Right Bunk Bed Mattress

What kind of mattress for bunk beds is best?

Bunk bed safety and sleep quality are important considerations to account for when making your choice of mattress.

To that end, consider a mattress that is:

Low Profile

The ideal thickness for a bunk bed mattress, specifically for the upper bunk, is about six or seven inches. A low mattress height will maximize the efficacy of the safety rail and increase the available headroom, while still being thick enough to provide comfort and support. Naturally, if your bed has higher guard rails, you can enjoy a thicker mattress.

Quiet Model

Sharing a bunk bed can be tricky, especially if the top sleeper is a tosser and turner on a creaky mattress. Again, for the top bunk especially, consider an all-foam mattress to reduce nighttime disturbances.

Lightweight

A thick, heavy mattress on the top bunk will pose a safety risk to both children. Always check the listed maximum weight capacity for your particular bunk bed — then find a thin, light mattress to match.

Temperature Control

Hot air rises, meaning the top bunk will always be a few degrees hotter on those warm summer nights. If you can find bunk bed mattresses with cooling technology, you’ll be able to ensure a comfortable night’s sleep for both people, no matter the weather.

For many families, bunk beds are temporary. Your kids may grow out of a bunk bed mattress, however, it’s best to spend a little extra now for a durable, comfortable mattress so you can get the most out of it. You can always repurpose the mattresses into a larger bed after your children outgrow their bunk beds by pushing them together. If you’re wondering what size two twin beds make, it’s about the size of a king mattress.

Equipping Your Bunk Beds with Casper Mattresses

Casper mattresses come in the three most popular bunk bed sizes: twin, twin XL, and full (as well as queen, king, and California king for any uncommon bunk beds). Between our four unique mattress types, you’ll be able to find something for both top and bottom bunks, including:

• All-foam or hybrid compositions for a creak-free sleeping experience
• Several varied layers for a uniquely comfortable feel
• Perforated, breathable foam for advanced cooling technology
• A durable base layer across all mattress models, plus additional foam, plush top layers, gel pods, and ergonomic zones for increased support

We know kids can be picky, so try a Casper mattress for 100 nights, risk-free. Soon enough, they’ll be telling you that it’s bedtime.

Reviewed By

Jonathan Eilenberg

Jonathan Eilenberg is a Certified Professional Ergonomist (CPE) with a degree in Design and Environmental Analysis from Cornell University, specializing in Human Factors and Ergonomics. His expertise in biomechanics and ergonomics has significantly contributed to improving workplace productivity and comfort. With over six years in occupational injury prevention, Jonathan now applies his knowledge at Casper, developing biomechanically supportive mattresses, emphasizing proper sleep posture to enhance comfort and recovery. His work integrates ergonomic principles into everyday life, aiming to improve physical well-being through thoughtful design.