Here’s the SPF You Actually Get When You Apply Sunscreen Sparingly [Updated]
by Beth Skwarecki on Vitals, shared by Beth Skwarecki from Lifehacker on (#3SP8D)
A sunscreen labeled "SPF 15" should let you spend about 15 times as long in the sun before you burn. Pretty awesome, right? Unfortunately, most of us don't get that level of protection because we don't apply enough. What you're likely getting: a mere SPF 3-5.