SPF stands for “Sun Protection Factor.” This number represents a measure of how well a sunscreen product helps protect against UVB rays. So, the higher the SPF value, the greater the protection against sunburn. For example, a product with SPF 30 filters approximately 97% of UVB rays, according to the Canadian Cancer Society.2 Dr. Daniel Sugai recommends looking for a moisturizer with SPF that is “broad-spectrum,” which helps protect against both UVA and UVB rays.