To determine the right firmness level for your bed, there are a few factors to consider: Your preferred sleeping position side sleepers may prefer a softer mattress, while back sleepers may need a firmer one. Your body weight heavier individuals may need a firmer mattress for proper support. Any existing back or joint pain a medium-firm mattress may be best for those with back or joint pain. Personal preference ultimately, the best firmness level for you will depend on your own comfort preferences. It may be helpful to try out different firmness levels at a mattress store or read reviews from other customers with similar preferences to guide your decision.