Mattress Foundation Sizes and Dimensions Guide

You’ve done all the hard work of finding the perfect mattress. You’ve laid on countless floor models, testing each one for comfort. You’ve made sure it’s not too soft and not too firm. You even brought your pillow from home to really get the authentic experience. But wait. How are you going to support that new mattress?

Mattress foundations are an important part of the investment in a new mattress. They help improve sleep quality while also helping to ensure the long-lasting comfort of a new mattress. Mattress foundations also determine the height of a bed. This can be helpful with the ease of getting in and out of bed.

People often wonder why they can’t keep a mattress on the floor. Besides the lack of visual appeal and the difficulty of getting in and out of bed, keeping a mattress on the floor will completely change your mattress temperature. A proper foundation allows for better air circulation. Increased air circulation makes the mattress and the person sleeping in it much cooler than if it were on the ground.

A proper foundation also helps extend the life of a mattress. The wrong foundation can reduce the effectiveness of a mattress, which in return can reduce the quality of sleep.

The easy part of the purchase is that mattress sizes are used to determine the size of mattress foundations. The most important part is picking out the right size based on your sleeping needs. In this post, we’ll cover all the different dimensions and unique traits to help find the best mattress foundation.

Twin Size Mattress Foundation

A twin bed foundation is 38 inches wide and 75 inches long. These are the smallest beds available and are often purchased for children. Twin mattresses and their foundations can also accommodate single sleepers who are not very tall. Twin foundations are also the cheapest due to their size. Bunk beds typically come in twin size, although sizes do vary depending upon the setup. These are also best for fitting a bed into a small space.

Twin XL Mattress Foundation

A twin XL foundation is 38 inches wide and 80 inches long. These are best for a single person who doesn’t need a lot of room to turn when they’re sleeping. Twin XL mattresses are good for taller individuals because they longer. Twin XL mattresses are also the most common beds that are seen in college dorms.

Full Size Mattress Foundation

A full foundation measures 54 inches wide and 75 inches long. Full size beds are a great fit for single sleepers who need more room when they sleep. A full bed allows them enough space to roll over without getting too close to the edge of the bed. These are also common in guest rooms as they do not take up as much room as larger beds.

Queen Size Mattress Foundation

A queen bed and foundation, like its corresponding mattress, is 60 inches wide and 80 inches long. A queen mattress and foundation is a good fit for couples without kids. It’s also good for couples that are shorter than 6 feet tall. Queen size mattresses and foundations are also a good fit for couples that don’t move frequently while asleep.

King Mattress Foundation

A King foundation measures 76 inches wide and 80 inches long. A king mattress and foundation is a great fit for couples who enjoy having space in bed. Having so much space allows for more room to move without bumping into another person. A king size mattress is also a good fit for couples who have kids that come into bed on occasion. A king size bed would not be a good choice for a smaller room.

California King Mattress Foundation

A California king, also known as a Western king, measures 72 inches wide and 84 inches long. While the California king bed is slightly more narrow, it has more length. This is the best option for couples with a taller partner(s) because of the extra length.

What is a Mattress Foundation?

Simply put, a mattress foundation provides support to your mattress. It’s placed underneath the mattress and helps maintain the mattress’ shape. This allows for maximum comfort and a higher quality night of rest.

Foundations are modern-day box springs. They have solid or slatted surfaces and are used in the same way as a box spring. Foundations are best paired with foam and hybrid mattresses because both mattresses need stable support that a box spring cannot provide. Some modern bed frames have a stable foundation built into the frame.

While foundations do enhance comfort, their primary purpose is to support and extend the life of your mattress. Many mattress warranties actually require you to properly support your mattress. They will even specifically outline what you need. Most modern beds require a specific foundation with a slatted surface.

Mattress Foundation vs. Box Springs

While box springs used to be standard in most homes, modern mattresses require a different type of support. Box springs are made with wooden rails and an inner coil system. These coils are often bouncy, resulting in an unstable bed. Box springs should only ever be used with an innerspring mattress.

More modern mattress foundations are usually made with wooden rails and wooden slats. As opposed to coils, these slats have no bounce. As a result, a foundation provides a more stable support for a mattress. A foundation is an ideal choice for latex, memory foam, and hybrid mattresses.

Things to Consider When Buying a Mattress Foundation

The primary goal is to always make sure that your mattress is completely supported. This will help provide an excellent night of sleep while also ensuring proper mattress care. While some foundations may be larger due to stylistic choice, a mattress foundation should never be smaller than its mattress.

Mattress Size and Number of Sleepers

An important thing to consider when buying a foundation and a mattress is how many people are sleeping in the bed. If you’re solo sleeping, you can opt for a twin, twin XL, or full size mattress and foundation. A good option for single adults will likely be a full size as it allows for more turning throughout the night.

Couples should choose between queens, kings, and California kings based on bedroom space and budget. Choosing the right bed is a long term commitment, so couples should also consider potential children that will be spending time with them in bed.

Bedroom Space

You also want to consider how much available space you have in your bedroom. While it may seem nice to have a king bed, it won’t look good if the new bed takes up the entire room. Below is a table with basic guidelines for how big a room should be in order to fit each bed size in it.

Mattress Type

Once you’ve determined how large of a bed you can purchase, it’s important to consider your mattress type to make sure you choose the correct foundation. There are plenty of different options available, and it’s important to understand how they need to be supported so you don’t void your warranty.

Memory Foam

Memory foam mattresses can be placed on a slatted foundation or a solid foundation. If you’re opting for slats, make sure they are at most 2.75 inches apart. By doing so, you ensure that your mattress is properly supported. Another option is getting a solid foundation that doesn’t have slats. Solid foundations create stable support to prevent the mattress from sagging.

Latex

Latex mattresses have a reputation for being quite durable. To best support one, place it on a slatted or solid base. As with the memory foam, this will prevent any potential sagging. If using slats, make sure that they are no more than 2.75 inches apart.

Hybrid

A supportive base is also needed for the hybrid mattress. Your best options for this include the solid base and a bunkie board. Both options will help prevent your mattress from sagging. You can also use narrow slats for a hybrid mattress. As always, make sure the slats are no more than 2.75 inches apart from one another.

Innersprings

While innerspring mattresses are best paired with a box spring, these mattresses can also go on a slatted or solid foundation.

Foundation Types and Styles

Slatted Foundation

A slatted foundation is commonly made of wooden slats. These slats are typically 2-2.75 inches apart from one another. This spacing is ideal for support to make sure mattresses don’t sag. Some slatted frames have wider spaces between slats, and as a result, require bunkie boards or other supports.

The slats lay across the bed frame in order to fully support the entire mattress, providing extra durability.

Slats typically result in a lower bed as they are usually about half an inch thick. Because they are not heavy, they are ideal for people who are unable to lift much weight. The main downside to slats is that they can slide and move if not installed properly. This can result in mattresses sagging.

Platforms

Platform beds are a large, sturdy base that supports a mattress. A platform can sometimes have slats, depending on the manufacturer. These can be lower to the ground, although higher platforms are readily available for purchase.

Platforms are the most stylish option for a bed foundation. They often come with an option for storage, allowing you to maximize the space underneath your bed. While providing a sturdy base, a platform creates a firmer surface. This surface can cause some minor sleep discomfort, although a proper mattress will help eliminate that.

Bunkie Boards

Bunkie boards are a thin but solid board that is often covered in fabric. While they were initially made of plywood, Bunkie boards are now made of more advanced material, including steel. The flat board can be used between a mattress and a box spring or a slatted base with slats that are too far apart.

The nice thing about a bunkie board is that it does not require any assembly. If slats are not working for your bed, a bunkie board is a good replacement to maintain your mattress’ integrity.

Because a bunkie board is quite thin, it keeps a lower bed profile. They provide great mattress support because there are no gaps as there are with slats. On top of all this, a bunkie board makes very little noise because there is no room for it to move or shift.

Box Springs

As mattress technology has evolved, box springs are used less frequently. A box spring is simply a wooden box with a spring system inside, wrapped in cloth.

Box springs should be paired with innerspring mattresses only. While they provide a strong, flat surface, they won’t properly support most modern mattresses. They were initially made to absorb shock when mattresses were thinner.

A box spring does a good job of keeping the mattress off the ground. They can also provide extra height, which can be helpful for getting in and out of bed. However, due to their coiled springs, they can be quite noisy when you shift your weight in bed.

Common Questions

What is the difference between a box spring and a foundation?

A box spring has coils in it and should only be used with mattresses that have an innerspring design. Foundations can be a flat surface or have slats. These are used for memory foam or latex mattresses. Both will support a mattress, but box springs are mostly obsolete. Using them with most modern mattresses will void your warranty and cause damage.

Do I need a mattress foundation?

A mattress foundation will better support both a mattress and the person sleeping on the mattress. If you have an 18-inch mattress and half of it is holding its shape on the floor, you’re not getting the most out of the mattress. A foundation can also to cooler sleep. Purchasing a mattress foundation is recommended for the longevity of your mattress.

What is the best foundation for a mattress?

The best foundation depends upon the type of mattress you purchase. Most modern mattresses need slats or platform support. This includes memory foam, gel, and hybrid mattresses. Innerspring mattresses can use box springs for their foundation. When buying a foundation, it’s also important to consider your personal style and what you would like your bedroom to look like.

What is a foundation set?

A foundation set contains a frame for a bed. It also includes any slats or bunkie boards that will help support your mattress. A foundation set normally combines the stylistic choice of a platform bed with the functionality of a smaller foundation. It can allow you to have some stylistic choice while also maximizing space in your bedroom.

Do you need a box spring with a memory foam mattress?

A box spring should not be used to support a memory foam mattress. A memory foam mattress needs firmer support, which a box spring doesn’t provide. A memory foam mattress should be supported by either a slatted foundation or platform. A platform foundation is usually recommended if you have the space for it.

Conclusion

A lot of mattress foundation decisions come down to functionality. It’s important to consider the type of mattress you’re purchasing when looking at the corresponding foundation. If you’re buying a new mattress, be sure to get a new foundation along with it. Any old foundation that has been used for years is likely to have its own issue. Make sure to factor in your own personal style and bedroom size when choosing mattress and corresponding foundation.