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Firmness: Using our experience of testing over 100 different beds, we analyze how firm or soft a bed feels in comparison to other beds. We use a one through 10 scale with 10 being the firmest. 

Feel: We get physical with the mattress and see what the material feels like. This is different from firmness. Depending on the foam and materials of a mattress, we see if the bed is bouncy, slow-responding, pressure-relieving or plush and fluffy. 

Durability: It's difficult to tell exactly how long each bed will last because we don't test it for years on end. However, we are able to hypothesize a bed's firmness by looking at its construction. Hybrid or innerspring beds are more durable and last longer than foam mattresses. 

Best body type: Based on a person's body weight, we determine how accommodating a mattress is. We use different size sleepers to test the beds, and focus heavily on a bed's construction. 

Best sleeping position: Using different sleepers, we test the mattress in each sleeping position: side, back and stomach. 

Motion isolation: We use two people to test how well motion transfer across the bed is deadened, or place a glass of water at the edge of the bed to see how much it moves if we bounce around. 

Edge support: We analyze construction and physically lay on the sides of the mattress to get a gauge on how supportive it feels. 

Temperature: Instead of getting fancy, we rely on our own experience sleeping on the bed and a temperature gun. We are able to tell if a bed is cooling, breathable or hot by sleeping on it for a few nights. 

Smell: Mattresses in a box emit a smell once they're unpackaged like a new car does. Don't worry, it won't stick around. The smell will go away after 24 to 48 hours. However, some beds emit less of an odor than others.

Read more on how we test mattresses.