Sunscreen is supposed to protect you from exposure to UV light that could leave you vulnerable to sunburn, wrinkles and skin cancer. But is it really doing its job?

Consumer Reports investigated 65 sunscreen lotions, sprays and sticks with an SPF of at least 30 – the minimum level recommended by the American Academy of Dermatology. The magazine asked people to apply the sunscreen to their backs, sit in water for the amount of water-resistant time as labeled on the products’ labels, then exposed them to UV light and examined for redness the next day.

The report found 43 percent of sunscreens failed to meet the SPF claim on their labels, some missing their mark dramatically. The Banana Boat Kids Tear-Free, Sting-Free SPF 50 lotion and CVS Kids Sun Lotion SPF 50 both tested at an SPF 8.