Mattress Foundation Sizes and Dimensions Guide

Mattress foundations help you to sleep better and your mattress to last longer. Lifting your mattress off the ground keeps it clean and increases airflow; and better airflow gives you cooler, deeper sleep. The right bed foundation depends on the size of your mattress and what it’s made of.

The chart below has the height and width of the foundation recommended for each mattress size. Some foundations are the exact same dimensions as the mattress, while others are 2 or 3 inches longer and wider. What is best for you comes down to preference and how much space you have in your room.

Mattress Foundation Sizes and Dimensions

Mattress Sizes Foundation Dimensions
Twin 38 by 74 inches
XL Twin 38 by 80 inches
Full/Double 54 by 75 inches
Queen 60 by 80 inches
King 76 by 80 inches
California King 72 by 84 inches

Twin Size Foundation Dimensions

Most twin foundations are 38 by 75 inches. Twin mattresses are ideal for college dorms, apartments, and bedrooms shared by two or more sleepers. Many families with multiple kids like this size because two twin beds can fit easily in most bedrooms—and they are great for bunk beds, trundle beds, and loft beds!

Twin XL Size Foundation Dimensions

Twin XL foundations are 38 by 80 inches. Twin XL mattresses are five inches longer than the standard twin, making them a good fit for teenagers, college students, and adults who want to save space. There are bunk beds designed for twin XLs, too!

Full Size Foundation Dimensions

Full bed foundations 54 by 75 inches in size. For sleepers who need to save space in their bedroom but want more room to spread out, the full sized bed is a good fit. This bed is a bit small for most couples.

Queen Size Foundation Dimensions

Queen foundations are usually 60 by 80 inches. This is the most popular sized bed for both couples and singles: plenty of room for two people but small enough to fit in most bedrooms. Single sleepers who like to spread out love how much room a queen mattress gives them.

King Size Foundation Dimensions

The king bed foundation is 76 by 80 inches. King mattresses are the widest standard sized bed, and ideal for couples with large bedrooms. Split foundations are often king size because two twin XL mattresses are the same size as a king bed. Split king beds are great because they give both sleepers the ability to pick out a mattress that’s best for their own sleep style.

California King Size Foundation Dimensions

The long California king foundation is typically 72 by 84 inches. Four inches longer than the king, the Cal king mattress is great for tall sleepers. But it is two inches narrower, so you won’t have quite as much room to spread out. Both king and Cal king beds require large rooms, otherwise the space feels cramped.

Benefits of a Mattress Foundation

Having a mattress foundation keeps the bed clean by lifting it off the floor, one of the dirtiest places in most homes. It also supports the mattress evenly. This prevents the bed from sagging, denting, or wearing out prematurely. Foundations are an affordable way to make sure your mattress lasts as long as possible.

In addition to keeping your mattress up off of the floor, foundations also lift your mattress higher, making it easy to get in and out of bed. This is especially important for older sleepers or someone suffering from an injury. When the sleeper sits on the bed their feet should rest flat on the ground with their lap parallel to the floor.

Types of Mattress Foundations and Bed Frames

What’s inside a mattress is a big part of finding the right foundation for your bed. Memory foam, hybrid, and latex mattresses require sturdy, even support. Innerspring mattresses work best with a box spring.

Mattress Foundation

These are great for heavy mattresses like memory foam, latex, and hybrids. Mattress foundations have either a solid wooden board or slats as the base of the bed. Slats are narrow boards set no more than 3 inches apart side by side up the width of the bed frame.

The entire frame is covered in an anti-slip material, giving it a similar appearance to a box spring. Mattress foundations increase the height of the bed while providing the sleeper with even support.


Platform foundations are ideal for hybrid, memory foam, and latex mattresses. This foundation distributes the weight of these heavy mattresses evenly, helping them last as long as possible. Platforms have either one solid board or wooden slats as the base. Unlike mattress foundations, the platform doesn’t contain material to cover the board or slats supporting the mattress.

Adjustable Bed Frame

An adjustable bed frame gives sleepers the ability to elevate their head and feet with the help of a remote. Split adjustable frames are pretty common and are divided down the middle; these give each sleeper the ability to raise and lower their own side of the bed however they want. Split beds are typically made by placing two twin XL mattresses together.

Not all mattresses are suitable for an adjustable bed frame. Memory foam, hybrid, and latex mattresses are the best because their flexibility allows them to bend with the frame while still conforming to the sleeper’s body. Latex mattresses are stiffer than memory foam so a thinner mattress has an easier time bending with the frame.

Box Spring

The box spring is a wooden box filled with springs and is the oldest kind of foundation. It is only suited for innerspring mattresses. Box springs damage memory foam, latex, and hybrid mattresses because these are heavy beds and they may break the springs inside the box spring. When this happens, mattresses sag and wear out unevenly.


How much bigger than my mattress should my foundation be?

The size of your bed foundation ultimately comes down to preference but you should consider how much space you have in your bedroom. If you don’t have any room to spare, a foundation with the same dimensions as your mattress is a good choice. For those with plenty of space, a foundation 2-3 inches bigger than the mattress is a fine option.

What’s the difference between a box spring and a foundation?

A box spring is exactly what it sounds like: a wooden box full of springs. This is the oldest bed foundation and it is only compatible with innerspring mattresses. Any other kind of mattress is too heavy and may break the springs.

A mattress foundation is a wooden box that either has slats or a solid surface to support the mattress. It’s covered by no-slip material to keep the mattress from moving around. Foundations provide consistent support for all kinds of beds, even heavy memory foam and latex mattresses.

How tall should my bed foundations be?

Your foundation should be between 16-25 inches tall, depending on how tall you are. You want the top of the mattress to be level with your knees. This height makes it easier to get in and out of bed. If you can sit on the edge of the bed with your feet flat on the ground and your knees bent at a right angle, your bed foundation is tall enough.

What kind of foundation is best for a memory foam mattress?

Memory foam mattresses are heavy and need a foundation that can support their weight evenly. A mattress foundation for a memory foam bed should have slats spaced no more than 3 inches apart to prevent sagging. Platforms and adjustable frames are also equipped to handle this kind of mattress. Box springs are not a good choice because they aren’t designed to support a heavy mattress.

Can I put my mattress on the floor?

We recommend you don’t put your mattress directly on the floor. Without a foundation, the mattress doesn’t get the support it needs and ends up wearing out faster. Also, the floor is one of the dirtiest parts of most homes and it’s best to keep your mattress as clean as possible.

Summing it Up

Everyone should have a mattress foundation—it keeps your bed clean and extends the life of your mattress. Buying a foundation is an affordable way to make sure your mattress lasts you as long as possible. And it provides you with healthier, cooler, more supportive sleep.

If you and your partner have drastically different sleep styles, consider getting a split foundation. Split beds make sure you each have the customized support you need to get your best sleep. Find the best foundation by considering your mattress’s materials, mattress dimensions, and the size of your room.

This article is for informational purposes and should not replace advice from your doctor or other medical professional.

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