La Roche-Posay, ringing in $18.82 per ounce, scored lower overall than No-Ad, 59 cents per ounce.

And it doesn't matter what type of sunscreen you use. No one type—spray, cream, or lotion—protected best. Consumer Reports found three best buys:

Up & Up Sport SPF 30 (Target) No-Ad with Aloe and Vitamin E SPF 45 Equate Baby SPF 50.

The Up & Up is a spray while the other two products are lotions.

But with sprays, some took more than 30 seconds to dry, but Coppertone Sport Ultra Sweatproof SPF 30, a top pick, dried especially fast.

Consumer Reports had an outside lab determine whether products met their labeled sun protection factor (SPF), which refers to UVB rays, and how well they blocked UVA.

Although the Food and Drug Administration proposed a one- to four-star labeling system for UVA protection in 2007, it's still not in effect, and most tested products simply claim "broad-spectrum protection."

Most claim water resistance for 80 minutes. Consumer Reports applied those to volunteers' backs; their backs were submerged in water for 80 minutes and then exposed to UV rays. Two that claim water resistance with no specified time were tested for 40 minutes.

But even though you should always wear sun screen, according to Consumer Reports, there are some things to look out for.

Retinyl palmitate, often found on the back of the sunscreen bottle among the inactive ingredients, is a type of topical vitamin A. It is an antioxidant that animal studies have linked to an increased risk of skin cancers. In skin, it converts readily to retinoids, associated with a risk of birth defects in people using acne medications containing them. As a precaution, pregnant women may want to avoid sunscreens with retinyl palmitate.

No matter what though, doctors told Consumer Reports not to rely on sunscreen alone. The report urges people to wear protective clothing and limit time in the sun. Sunscreen should be water resistant, with an SPF of at least 30. Above 30, there's not much more protection. People need to reapply any sunscreen every 2 hours or so anyway and after swimming or sweating.

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