Generally, the memory foam density of a tempurpedic mattress is 5 lb. The difficulty in this is that while for some people 5 lb is too firm and tough, this is why mattresses with the density of 3 lb and 4 lb are introduced.
It is advisable to shop for tempurpedic mattress that has a density of 4 lb because the one that has a density lower than it would not last longer and are very soft. However, a memory foam mattress of 4 or 5 lb normally last for more than 10 years.
Source link: http://www.americanchronicle.com/articles/viewArticle.asp?articleID=43715
Related:
Mattress for hospital bed
Travel trailer mattress
How to inflate an eddie bauer air mattress