Hi liaozhongchao,
I would also keep in mind that there are no “standard” definitions or consensus of opinions for firmness ratings and different manufacturers can rate their mattresses very differently than others so a mattress that one manufacturer rates as being a specific firmness could be rated very differently by another manufacturer. Different people can also have very different perceptions of firmness and softness compared to others as well and a mattress that feels firm for one person can feel like “medium” for someone else or even “soft” for someone else (or vice versa) depending on their body type, sleeping style, physiology, their frame of reference based on what they are used to, and their individual sensitivity and perceptions. There are also different types of firmness and softness that different people may be sensitive to that can affect how they “rate” a mattress as well (see post #15 here) so different people can also have very different opinions on how two mattresses compare in terms of firmness and and some people may rate one mattress as being firmer than another and someone else may rate them the other way around. This is all relative and very subjective and is as much an art as a science.
The previous Tuft & Needle mattress certainly wasn’t a “super firm” mattress and most people would have probably regarded it as somewhere in the medium firm range.
Depending on the person and on the materials in the mattress some “medium” or “medium firm” mattresses may feel softer and some may feel firmer but most of the mattresses that are rated as “firm” would probably feel firmer for most people.
There is more about Tuft & Needle and many of the other “simplified choice” mattresses in post #2 here in the simplified choice mattress topic.
If you are looking at online options then outside of the simplified choice list the mattress shopping tutorial also includes several links to lists of many of the better online options I’m aware of (in the optional online step) that include many different types and categories of mattresses in a wide range of budgets and firmness levels that would also be well worth considering.
When you can’t test a mattress in person then the most reliable source of guidance is always a more detailed phone conversation with a knowledgeable and experienced retailer or manufacturer that has your best interests at heart and who can help “talk you through” the specifics of their mattresses and the properties and “feel” of the materials they are using (fast or slow response, resilience, firmness etc) and the options they have available that may be the best “match” for you based on the information you provide them, any local testing you have done or mattresses you have slept on and liked or other mattresses you are considering that they are familiar with, and the “averages” of other customers that are similar to you. They will know more about “matching” their specific mattress designs and firmness levels to different body types, sleeping positions, and preferences (or to other mattresses that they are familiar with) than anyone else.
Phoenix