Basically too soft. Mattresses rated 1 will have plenty of plush cushioning and a lot of sink. This is rarified air for soft mattresses.
A very soft and very common mattress type. Plush with noticeable sinkage.
The most common range for mattresses. Right in the middle of soft and firm, with some minor sink and contouring.
Very firm and solid, with little softness and sink.
On the other end of the spectrum from 1. This is the firmest you can go.
Each of these firmness levels has implications outside of comfort and preference. For example, firmer mattresses tend to work better for people with very bad back pain and soft mattresses are better for people who are much lighter in weight.
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