I am looking for some kind of guide on determining the best thickness and firmness of a mattress for me. From what I have read on the site, I’m a side sleeper and need a softer mattress. But I’m also heavy, so I will need a firmer mattress. The mattresses that “Feel Good” at the stores actually make my tail end sink or make me hammock a bit. The mattress that is a hair firmer than I like kept me straight and is probably the wisest choice. I just have an unusual body shape like a more short waisted middle-aged mr. incredible. My shoulders need to sink in pretty deep to straighten out my spine. From that angle, is a 3 inch comfort layer even enough? I was thinking about doing a medium topper over medium-firm core. On a 9 inch medium/medium latex mattress I felt like I was bottoming out. So I’m looking for a 12 inch, but maybe there’s more to this tale that I am missing.
Hi Absentminded,
Unfortunately … there are just too many variables to produce a “chart” that would build a mattress by the specs. There are some guidelines on the site however that can provide some general guidelines. The most helpful would probably be the body type guidelines here … the sleeping position guidelines here … and the overview about putting the layers together which includes information about how different types of layering can affect and change both of the first two guidelines. The sub pages in the same section go into even more detail.
In most cases though … mattress design theory is far more complex than most people may suspect or even want to know, and the best approach is usually to find an expert that already knows what you would otherwise need to learn (and this could take years) and that can give you the guidance you need to help you make your best decisions based on your experiences on specific mattresses. Your personal experience on a mattress in terms of PPP (Pressure relief, Posture and alignment, and Personal preferences) is always much more accurate and valuable than knowing the comfort specs of a mattress which may work “in theory”.
In other words … putting your efforts into finding the best outlets that already have the knowledge along with the quality, value, and service that you would want is usually more effective than trying to learn enough to become an expert yourself or trying to design a mattress based on the averages of either a chart or specs only to find that you weren’t quite as 'average" as you may have thought 
If you let me know the zip or city you live in … I’d be happy to let you know of any manufacturers or better outlets I may know of in your area.
Phoenix
I got the same problem. Tried memory foam and it just makes everything worse. Bought a Simmons firm mattress w 13.5 gauge makes everything hurt, bought. Plush with 15.5 gauge makes everything hurt even worse. The problem is these mainstream manufacturers either have something really soft or really firm… You seem like me where u need a mattress with good support but pressure relief. I forgot the company but it sells innersprings and coils and has something w a money back guarantee I am going to order it. Phoenix mentioned the site in other posts. It’s 14.5 gauge so that’s totally medium firm. It soft and not firm… The only other manufacturer mainstream that has a medium gauge 14.5 gauge is Serta but not sure what models, I think the problem is they add do much foam over these innersprings they barely work like 5 inches but they mix up firm foam and plush foam for a fancy feel. But then it doesn’t conform to u the springs cannot work with so much padding… If u let me know how it goes.vi am ordering tomorrow.
I think the best option for you is to try out different types of mattresses. you can go to a shop and have a look. It will be more feasible to choose then. You can also try different mattress types to find the one which fits you the most.