Foundation or Box Spring?

Is there a difference between a foundation and a box spring?

When shopping for a new mattress, you’ll find the word foundation being used in place of “box spring.” This is because foundations have taken the place of traditional “box springs” in the mattress world.

Traditionally, it wasn’t just the mattress that had coil springs inside, box springs actually had “springs” in them too. They were generally thicker, stronger and had less ‘give’ than the springs used in the mattress. The purpose of a box spring was to add support and help absorb weight — kind of like how shocks work on a car.

Using metal springs in a box spring is a fairly expensive process, and these days is rarely found except in very high-end mattresses. Hastens, Royal-Pedic and Vi-Spring are a few high end mattress manufacturers who are still making real box springs.

Over the years, box springs have evolved into foundations.

Instead of consisting of springs, foundations tend to be made with a series of V-shaped steel modules that form a grid, and have very little give. They help distribute weight evenly, help the mattress feel the way it should feel, and last as long as it should. They’re also less expensive to manufacture.

Of course, there’s quite a bit of variation between foundations in the construction. For example, some of them don’t have any steel modules at all. They might be made of just wood only. Usually a manufacturer will make those when the mattress calls for a very hard surface with absolutely zero give.

How do I know what kind of foundation my mattress needs?

99% of the time, the foundation that comes with your mattress is the right kind to use. They’re made to work with the mattress. But here are a few extra guidelines:

Spring-free memory foam mattresses work best on a super hard, non-yielding foundation or platform surface. Mattresses made with innersprings work well on foundations with some give, and in some cases no give (as is the case with Saatva).

You don’t “have” to use a foundation. For example, if you have a platform bed, you don’t use a foundation, you just put the mattress directly on the platform.

Some innerspring mattresses will feel different on a platform bed vs. a foundation. This is because most foundations do absorb about 50% of the overall weight, which affects the way the mattress conforms to your body.

image of foundation

A foundation provides support for the mattress and helps distribute weight evenly.

Can I use my old boxspring/foundation with a new mattress?

It depends. If it’s 10 years old, then I would replace it. Remember, they go bad just like mattresses do. Over time they can develop weak points that can potentially affect a new mattress.

In addition, older box springs may not comply with the federal mattress flammability standard, 16 CFR Part 1633, which went into effect on July 1, 2007.  Fire tests show that when using a new 1633 compliant mattress on a pre standard box spring, the mattress will fail the flammability test.  So using older box springs with a new mattress may pose a safety risk.

If it’s less than 2 or 3 years old, then you’re usually fine. Just make sure it’s the best type of foundation for whatever mattress you’re buying. Example, if you’re planning on getting a spring-free memory foam mattress, I wouldn’t put it on a box spring with any “give” to it. They need to be on a very firm surface with no give to work properly.

– Sean

Disclosure of Material Connection: Some of the links in this post are affiliate links.  This means if you click on the link and purchase the item, I will receive a referral fee at no additional cost to you. Regardless, I only recommend products or services I’ve used and tested personally.


  • Cheryl

    I always advise people to go with platform beds. The extra box spring is unneeded. It just costs extra money. On top of it, most of them are really just foundations like you said. Here’s 10 Good Reasons why platform beds win this debate:

    Most important is #1, coil springs have been related to higher rates of cancer. It’s really surprising to me that this hasn’t been covered more extensively by the media.

  • Aerogenous

    So then I could actually forego a boxspring and use, say particle board as a foundation. I really want to lower my mattress as it’s on an old 1850’s rope bed and the modern rails could only screw in one spot so my mattress is like 32″ from the floor. I need a stool to get in it.