Mattress Foundation Sizes Guide

We hope you love the products we recommend. Our research is supported by you, our readers. When you buy something through our links, we may earn an affiliate commission (at no additional cost to you). Learn more

If you haven’t heard the news: box springs are out and mattress foundations are in. There’s just so much to love about a good quality mattress foundation, from their firm support to the fact they’re durable enough to outlast any set of box springs.

However, just like with box springs, you have to be sure your mattress foundation both corresponds to your mattress size and fits your bed frame. Mattress foundations have to sit inside or on top of your bed frame and hold up your mattress, so their dimensions will be pretty similar to your mattress size.

In this post, we’ll talk about common mattress foundation dimensions, the benefits of a mattress foundation, and the kinds of mattresses that work best with these bases.


Twin beds are great for dorm rooms, multi-purpose guest rooms, teeny apartments, and any other bedroom with limited square footage. A twin mattress is the smallest mattress size intended for adults, coming in at just 38 by 75 inches. Its corresponding mattress foundation will also be this size, allowing the edges of your mattress to align perfectly with those of the foundation.

Twin XL

A twin XL bed is a good choice for taller sleepers looking for a compact bed size. They’re still only 38 inches wide, but a twin XL mattress and mattress foundation are both 80 inches long, allowing for some extra leg room and making them the best fit for tall individuals who still need a narrow bed for a small space.


If you want a shorter, wider bed, the 54 by 75 inch full or double mattress/foundation combo may be for you. Full beds offers sleepers under 6 feet tall a few extra inches of width without taking up too much additional space. The full is also called a double bed because it’s considered the smallest bed two adults can sleep on, but in reality, this bed is not all that comfortable for two sleepers. Most of the time, a queen or larger is the best choice for couples.


Queen bed dimensions offer the perfect balance between roominess and compactness, which is why the queen is the most popular size bed. At 60 by 80 inches, the queen size mattress and foundation is the first bed that truly offers sufficient space for couples. If you’re a single sleeper looking for enough width to have some wiggle room, or you’re a couple with a smaller master bedroom, the queen may be the right size for you. 


Couples with larger rooms or who feel the queen size bed isn’t big enough may find the standard king beds are the ideal choice. At 76 by 80 inches, this is the largest standard mattress size as far as sleeping surface. Its extra width will accommodate even the most active combo sleepers. Just watch out for your room dimensions, as kings can make smaller rooms feel overly crowded.

One thing to keep in mind is kings may need a split foundation. This simply means that instead of a single, king size foundation, you have two twin XL foundations. The split foundation can make moving less of a hassle and also makes the foundation less prone to sagging.

California King

The California king bed comes in at a whopping 72 by 84 inches, and the extra length can make this the perfect mattress/foundation for extra tall sleepers. If you’re well over 6 feet tall, you might consider a California king over a standard king even if you’re a single person.

Like with the standard king, you may want to purchase a split foundation for a California king mattress, though you will need one made specifically to fit a Cali king bed (two twin XLs will be too wide and short for the Cali king frame).

What is a Mattress Foundation?

A mattress foundation is a type of bed base meant to offer firmer support for your mattress. It’s a rectangular frame—normally made of wood or metal—with metal or wooden slats stretched across it at regular intervals. 

Depending on the manufacturer, these slats may be flat or curved upward to provide additional support in the middle of the mattress and help stave off sagging in both the mattress and foundation itself. 

Unlike box springs, mattress foundations have little to no give. That means they won’t collapse under a mattress’s or sleeper’s weight. While you may miss the bounciness of box springs, the more rigid support of a foundation is actually better because it can provide more stability and extend the life of your mattress.

Benefits of a Mattress Foundation


Mattress foundations have a lot of benefits over putting your mattress on a bed frame alone or laying it on the floor.

Additional Height

First and foremost, foundations help raise your bed to the correct height. While some people like the low profile afforded by placing their mattress on a platform bed or directly on the floor, the ideal height for a bed is around knee-high (about 24 inches). Platforms can raise your bed height by up to 16 inches, getting it closer to the 24-inch mark and making it easier to get in and out of bed. This might not be too important for healthy young people, but it can be vital for seniors and people with disabilities.

Air Circulation

Another great benefit of the foundation is it helps increase air circulation under your bed. If you lay your mattress on a foundation, as opposed to the floor, it will help get air flowing underneath the bed, cooling it down and discouraging mold growth. The added height of a foundation can also help improve airflow even if your mattress is already in a bed frame.

Firm Support

Mattress foundations help shore up support. The slats in a foundation are normally closer together than those of a bed frame, and many foundations also come with the option of adding more slats. Having slats at 2 to 3-inch intervals is especially important for heavier mattresses like latex and memory foam beds, as these mattress types weigh so much their bottom layers may sag between the slats if they’re spaced too far apart. 

Warranty Coverage

Depending on the type of mattress you get, you may have to purchase a foundation. Lots of mattress warranties specify that if you put the mattress on the floor, directly on a bed frame, or even on a set of box springs, its coverage will be voided. However, most of the time, warranties list both mattress foundations and platform beds as suitable bases. Check your mattress warranty to be certain, but normally a mattress foundation has you covered.


What’s the main difference between box springs and mattress foundations?

Unlike foundations, which are solid bases with rigid support, box springs are a network of steel coils fitted inside a wooden frame to support your mattress. Box springs offer more flexibility and bounce than a foundation. However, due to their coil support system, box springs can’t hold much weight, so they’re really only compatible with innerspring mattresses. 

Box springs are also less durable than foundations. While box springs lose their tension and break down quickly, often needing replacement before your mattress does, mattress foundations will hold up under pressure. Foundations usually last at least the lifetime of your mattress and may even outlive it. 

What mattress types are compatible with a foundation?

While traditional box springs can only handle lighter innerspring mattresses, mattress foundations are sturdy and durable enough to hold the weight of much heavier beds. They are compatible with pretty much all mattress types, including hybrid beds, memory foam mattresses, latex foam beds, and innerspring mattresses. Mattress foundations are especially recommended for heavy foam mattresses because they can help prevent sagging and extend their life expectancy. 

Can’t I just lay my bed on the floor and not worry about a base?

It’s inadvisable to lay your mattress on the floor because doing so puts it at risk of damage from dirt, moisture, pests, and mold. The floor is dirty, and that dirt has a much easier time transferring to your mattress if there’s nothing underneath it. Without the protective buffer of a base, your mattress might also be more vulnerable to water damage in the event of a plumbing leak. 

Being on the floor also makes it easier for pests to climb into bed with you. And since the floor offers no air circulation, your mattress can accumulate moisture, making it a breeding ground for mold, mildew, and bacteria. 

How much should I pay for a mattress foundation? 

Mattress foundation prices can range depending on the quality of the materials, size, brand, manufacturing location, and other factors. Generally speaking, you can expect to pay $100 to $600 for a mattress foundation. If you’re paying less than $100, you’re likely not getting a quality product. But if you’re approaching the $1,000 mark for a flat (non-adjustable) foundation, you need to consider whether your retailer is overcharging. 

What is a platform bed?

A platform bed is similar to a mattress foundation in that it’s a rectangular frame with bed slats running across it. Platform beds have legs and are made to stand alone, and they’re great if you want a low profile, minimalist look to your bed. 

Platform beds’ easy assembly also makes them a good option for people who don’t want to deal with setting up a lot of different components like rails, bed frame slats, headboards, footboards, box springs, foundations, etc. Some mattress foundations even come with detachable legs so they can double as a platform bed!

Are bed frames the same as foundations?

Mattress foundations and bed frames are not the same. Bed frames stand on four legs on the floor, and they normally include a headboard, footboard, and side rails. Mattress foundations, meanwhile, are just a support frame made to go on top of your bed frame rather than standing on their own. The two are intended to be combined, with the frame serving as the stand for the foundation and the foundation serving as the support for the mattress. 

Many bed frames don’t have enough slats to take a mattress without a foundation for support. If your bed frame has slats at 2 to 3-inch intervals, you won’t need an additional base. But most bed frames don’t come with too many slats, meaning you’ll need a foundation between the frame and your mattress. 

Bottom Line

A good mattress foundation is key to supporting and maintaining your mattress. Foundations offer tons of benefits, don’t cost a lot, and can extend the life of your mattress by months or even years. If it helps you go a few extra years before you have to drop a grand or two on a new mattress, your mattress foundation might just wind up paying for itself!

More To Explore