Firm foam density question

I recently went into a Mattress Firm store. I really liked the Sterns & Foster memory foam model that was the firmest in the store. It barely gave when you first got on it. He said it was 7.5lb foam on top.

Is all 7.5lb foam this firm? From what I’m reading it seems that density doesn’t always mean firmness. Where can I find this firm memory foam? I live in Charlotte, NC but would order from online if I knew what I was getting.

Thank you for the help.


Hi s1w999,

I would doubt that this is accurate (and in many cases some salespeople in the mainstream chain stores will tell you whatever they believe will sell a mattress) but it’s possible because there is 7 - 8 lb memory foam available in the industry although it tends to be used in much thinner layers and most of the mattresses that used it would have lower density layers of memory foam (or other types of foam) and then the support core would be polyfoam. No matter what the density of a single layer though it’s always most important to make sure you know all the specific layers and components inside any mattress you are considering (not just one of the thinner layers) so you can identify any weak links in the mattress and make more meaningful comparisons with other mattresses.

I looked at the Mattress Firm website and the only very firm Stearns & Foster mattress they list on their site is the Adele Ultra Firm and out of the 12.75" of the mattress it only includes 1/2" of memory foam buried inside the mattress where you wouldn’t really feel it. None of them include more than an inch of memory foam (also buried inside the mattress where you wouldn’t really feel it) or could be called a memory foam mattress. Is this the mattress you were looking at or was it another one?

If any of the ones they list are the one you tried then the memory foam in them wouldn’t be the main reason it felt firm to you and I would seriously question whether even the small amount of memory foam they contained was 7.5 lbs.

The density of memory foam has little to do with its firmness. As an example the 7 lb memory foam that Tempurpedic uses in some of their mattresses is softer than their 5.3 lb memory foam and the 4.1 lb memory foam they use is softer yet. The firmness of memory foam will also vary with temperature, humidity, the amount of time it is compressed, and the layers that are either over or under it (which will also be a significant part of what you feel). The density has much more to do with the relative durability of memory foam (5 lb memory foam and higher would be a high quality and durable memory foam compared to lower densities).

I would keep in mind that what you were feeling may not have been only from the 7 lb memory foam layer. There is a wide variety of diferent types of memory foam in every density (see post #9 here and post #8 here) so you would really be dependent on either your own personal testing to know if another mattress had a similar firmness level or you would need more detailed conversations with an online manufacturer to find out how their memory foam mattresses “feel” compared to other mattresses they may be familiar with. Many of the online memory foam retailers or manufacturers use the Tempurpedic memory foam mattresses as a comparison for how they feel so if you are considering an online purchase it may also be worthwhile testing some of the Tempurpedic mattresses that are widely available to get a sense of which one you would want to use as a reference point for an online purchase.

I would also make sure that you’ve read the tutorial post here which has all the basic information, steps, and guidelines that can help you make the best possible choices … and know how and why to avoid the worst ones (which would normally include Stearns & Foster along with the other major brands or any of the mattresses that were sold at most chain stores such as Mattress Firm).

Once you get to step 3 … the better options and possibilities I’m aware of in the Charlotte area are listed in post #2 here. You have some good quality/value options available to you in the area.