When it comes to sunscreen, how much you use is just as important as when and what you apply. A swipe here and a dot there just won’t cut it. “Most people only apply a percentage of the amount necessary, making an SPF 30 closer to an SPF 15,” says New York dermatologist Dr. David Bank.
One ounce of sunscreen—the equivalent of a full shot glass—slathered from head to toe is what you should aim for.
So we tested the full one-ounce dose and calculated just how much needs to be applied (to each body part) to protect skin and beat the burn. Full disclosure: It was quite greasy. Allot considerable rubbing-in time.