The grading is carried out according to our rating: the highest rated mattress comes in at #1 and the lowest at #5. Keep in mind this is just our top 5 of perhaps dozens reviewed. We could give you a choice of 10, but we find that 5 is best for most people to choose from. Regarding our Rating: This is based upon general comments online regarding each product, online reviews, product specifications, manufacturer’s and seller’s websites, response to questions we have asked regarding the product and even personal use in some cases.