Sunscreen Buying Guide

Our tests of dozens of lotions and sprays show that you can't always rely on the sun protection factor (SPF). That number is a measure of how well a sunscreen protects against sunburn, which is mostly the result of exposure to the sun's UVB rays. We also test for protection against ultraviolet A rays, which tan and age skin, and also, along with UVB rays, contribute to skin cancer. We found five sunscreens that did well enough against both UVA and UVB to recommend.

How We Tested

CR uses a testing protocol that is modeled on the one the Food and Drug Administration (FDA) requires sunscreen manufacturers to use. But as is the case with other products we test that have government or industry standards, we use those standards as benchmarks and develop our own methodology to identify differences in performance and give consumers a comparative evaluation.

We test only sunscreens with a listed SPF of at least 30 and are water-resistant (for 40 or 80 minutes, the two time periods the FDA permits water-resistance claims for). We buy the sunscreens for our tests off the shelf, the way consumers would and use three samples, preferably with different lot numbers, of each product. 

Each sunscreen is rated on three criteria: SPF, variation from SPF, and UVA protection. In addition, CR's trained sensory panel evaluates the scent and skin feel of the products.

SPF is a relative measure of how long a sunscreen will protect you from sunburn. Usually the number is explained as the amount of time it takes an individual's skin to burn when it's covered in sunscreen compared with when it's not. For example, if you'd normally burn after 20 minutes in the sun without sunscreen, an SPF 30 protects for 600 minutes, or 10 hours (assuming you apply and reapply correctly). But intensity and wavelength distribution of UVB rays vary throughout the day and by location. And no matter what SPF you use, sunscreen needs to be reapplied every two hours, or immediately when you get out of the water.

We also calculate a score for variation from SPF. This is a measure of how closely a sunscreen's tested SPF matched the SPF on the label.

The SPF number gives you no information on how well a sunscreen protects against UVA rays. That's why you need to look for a broad-spectrum sunscreen, which protect against both UVA and UVB. However, no sunscreen blocks 100 percent of UVA or UVB rays. The breakdown: SPF 30 blocks 97 percent of UVB rays, SPF 50 blocks 98 percent, and SPF 100 blocks 99 percent.

Alas, there are no trips to Tahiti for our sunscreen panelists—they go to a lab. To check for SPF, a standard amount of each sunscreen is applied a 2x3-inch rectangle on our panelists' backs. Then they soak in a tub of water. Afterward, each of those areas is exposed to five or six intensities of ultraviolet light from a sun simulator for a set time. About a day later, the six spots are examined for redness. The resulting SPF ratings reflect each product’s effectiveness after water immersion and are based on an average of our results for each sunscreen.

The UVA test we use allows us to differentiate the degree of UVA protection among sunscreens. To test for UVA, we smear sunscreen onto plastic plates and pass UV light through and measure the amount of UVA and UVB rays that are absorbed. That information is then used to calculate our UVA score.

What We Found

Of the 53 sunscreens in our ratings this year, 36 tested at less than half their labeled SPF number. That doesn't mean the products aren't protective at all, but you might not be getting the degree of protection you think you are.

These results aren't a fluke. We have seen a similar pattern in previous years' sunscreen tests. 

Missing the mark could mean you're not adequately shielding your skin. An SPF 50, say, that tests at less than half its labeled SPF in our tests would deliver an SPF 24 at the most, and sometimes far less. (The American Academy of Dermatology recommends using a product with an SPF of 30 or higher.)

In our tests over the years, we have not found a mineral (sometimes called natural) sunscreen—those that contain only titanium dioxide, zinc oxide, or both as active ingredients—that provides top-notch SPF and UVA protection and has minimal variation from SPF. None of the mineral sunscreens in our tests this year did well enough to make our list of recommendations.

The sensory aspects of sunscreen are important to many people. You're less likely to use a product if you don't like its scent or feel. Our sensory testing found many that did not feel heavy or sticky on skin, and in many cases these were also high-performing products.

Sunscreens come in a variety of fragrances. In addition to the classic beachy scent, the ones in our tests had tropical, floral, baby powder, citrus, herbal, and woodsy/outdoorsy notes. We also found that no fragrance doesn't always mean no odor. Many fragrance-free sunscreens had a slight plastic (think beach ball) or wet-clay scent. 

What's in Sunscreen

Skin cancer is the most common cancer in the U.S., and the benefits of sunscreens outweigh potential risks from their ingredients. 

That said, there have been a lot of worrisome reports about the health effects with sunscreen chemical ingredients such as oxybenzone and avobenzone. Some experts are concerned that these chemicals may be absorbed through the skin, leading to skin irritation, hormonal disruption—even skin cancer. Recently, the FDA called for more research on the safety and effectiveness of these chemicals.

The FDA is not saying that these ingredients are unsafe. However, some chemical UV filters, such as octinoxate and oxybenzone, have been found to cause hormonal changes in animals. Short-term research in people did not show any adverse effect. And one large animal study found that the inactive ingredient retinyl palmitate, one of a group of chemical compounds related to vitamin A called retinoids, may become carcinogenic when exposed to light. But that hasn't been studied in people. Taking pills that contain a different type of retinoid for skin conditions such as acne has been linked to birth defects. As a precaution, pregnant women may want to choose a sunscreen without the ingredient retinol palmitate or retinyl palmitate. 

CR experts say there is overwhelming evidence that sunscreen protects against skin cancer and other harmful effects of the sun, so consumers need to continue to use it on exposed skin while scientists do more research on the safety of sunscreen ingredients. 

If you are concerned about the chemicals in sunscreen you may wish to use a mineral sunscreen. The FDA has not raised any safety concerns with titanium dioxide or zinc oxide. But as noted above, the mineral sunscreens in our tests this year, and over the years, did not come in at the top of our ratings.  

Sun Protection

You can use less sunscreen if you follow other sun protection strategies, which everyone should do anyway. Research shows that people who rely on sunscreens alone tend to burn more than those who stay in the shade and wear long sleeves. Try to avoid the sun or stay in the shade when the sun is the strongest (10 a.m. to 4 p.m.), and dress right for the occasion. Wear a hat and clothing made from tightly woven fabric. Hold clothing up to the light; if you can see through it, the UV rays can get through, too.

When Using Sunscreen

Shake it. The directions might not tell you to do this, but it’s a good idea because it helps distribute the active ingredients throughout the sunscreen.

Use enough. Apply sunscreen 15 to 30 minutes before you go outside. For lotions, a good rule of thumb is to use a shot glass full (about an ounce) to cover your entire bathing-suit-clad body. Or think of it as a teaspoon per body part or area: 1 teaspoon for your face, head, and neck; 1 for each arm; 1 for each leg; 1 for your chest and abdomen; and 1 for your back and the back of your neck. For sprays, apply as much as can be rubbed in, then repeat. Regardless of which kind you use, reapply every 2 hours and immediately after swimming or sweating.

Use spray sunscreens carefully. The FDA has said it is exploring the risks of inhaling spray sunscreens. Until we know more, our experts say to avoid using sprays on children, and do not spray them directly on your face. Instead, spray sunscreen onto your hands, then apply it to your face. If you use a spray on a child, spray the sunscreen into your hands and rub it onto the child’s skin. Sprays are flammable, so let them dry before going near an open flame.

Bottom Line

Based on our findings, it’s especially important to check our ratings for a sunscreen that did well. If you can’t find one of those, the results of our tests over the years indicate that choosing a sunscreen with chemical active ingredients and an SPF of 40 or higher will give you a better chance of getting at least an SPF 30. Using any sunscreen is better than using none, but it’s just one part of a smart sun protection strategy. 

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