Sunscreen and sun-protective clothing: reading the labels

This page is general information, not medical advice. Your own doctor or care team is the right source for questions about your skin, diagnosis or treatment.

A sunscreen label contains different kinds of information: a protection rating, the range of rays covered, water-resistance testing, ingredients, and instructions for use. Those details answer separate questions. A large rating does not explain every property, and the words on the front of a container do not replace its directions.

What SPF and broad spectrum mean

The U.S. Food and Drug Administration's sunscreen reference defines sun protection factor, or SPF, in terms of the ultraviolet exposure needed to cause sunburn with sunscreen compared with exposure without it. The test primarily indicates protection against UVB rays. UVB and UVA are types of ultraviolet radiation, the invisible radiation in sunlight.

The FDA explicitly explains that SPF is not directly related to the time spent in the sun. Solar intensity differs with the time of day and location. A protection rating therefore cannot be turned into an assurance about how long someone can remain outside. The rating also says little about whether the sunscreen has been applied evenly or remains on the skin.

Broad spectrum means protection against UVA as well as UVB. The FDA distinguishes that label from the SPF rating, which mainly concerns UVB protection. These are complementary pieces of information. The agency describes sunscreen as part of a wider set of measures, with clothing and shade still needed.

The FDA describes regular use of broad-spectrum sunscreen with SPF values of 15 or higher. The American Academy of Dermatology recommends broad-spectrum, water-resistant sunscreen with SPF 30 or higher. These are the respective agencies' general descriptions, rather than a product recommendation or a plan for an individual's skin.

Water resistance and reapplication

The FDA says there is no waterproof sunscreen: sunscreen eventually washes off. Water resistant refers to a tested claim about protection while swimming or sweating. It does not mean that the sunscreen stays effective indefinitely, nor that reapplication directions no longer apply. A label's water-resistance claim and its general directions need to be read together.

The FDA requires a water-resistant label to state whether protection remains effective for 40 minutes or 80 minutes during swimming or sweating. Its general guidance says to reapply at least every two hours, and more often when swimming or sweating. The American Academy of Dermatology likewise connects reapplication after swimming or sweating with the directions on the container.

The label describes tested conditions and instructions. It does not measure how much sunscreen remains on a particular person's skin during an outdoor day. Water resistance should not be read as an assurance that the original application is enough after changing activities.

Amounts and timing in agency guidance

The FDA's general directions describe application 15 minutes before sun exposure and at least one ounce to evenly cover an average-sized adult's or child's body, avoiding the eyes and mouth. Its reference identifies often-forgotten areas such as the ears, neck, hands, tops of the feet, and exposed scalp.

The American Academy of Dermatology describes about 1 ounce as the minimum most adults need for skin not covered by clothing, and application to dry skin 15 minutes before going outdoors. It notes that the amount needed varies with body size. This helps explain why an amount in a general reference is not a measure tailored to every person.

The FDA also notes that instructions can differ according to the sunscreen's form. Lotion, cream, stick, gel, and spray are examples of forms rather than protection ratings. The active-ingredient list and the directions are separate parts of the label. The agency's descriptions do not identify a best brand.

The FDA also describes storage and expiration information. It recommends keeping sunscreen containers out of direct sunlight and excessive heat, including by placing them in shade. An expiration date concerns the stability of the contents, whereas a water-resistance statement concerns testing during use. Neither is a replacement for the directions. These separate label details can help explain why a rating alone gives only part of the information.

Mineral and other filter types

The American Academy of Dermatology distinguishes mineral, also called physical, sunscreens by the ingredients zinc oxide, titanium dioxide, or both. It describes other active-ingredient types as chemical sunscreens and mixtures of the types as hybrids. These labels refer to the filters used; they do not replace broad-spectrum, SPF, or water-resistance information.

The academy explains that these sunscreen types form a layer that absorbs the sun's rays, and that mineral filters also reflect rays. The FDA's reference similarly describes absorption or reflection before ultraviolet radiation reaches and damages skin. This is an explanation of how filters work, not a ranking of formulations. Questions about a person's skin sensitivity belong with a doctor rather than with a general label comparison.

Fabric coverage and UPF

The Skin Cancer Foundation's clothing reference defines ultraviolet protection factor, or UPF, as a measure of how much UVA and UVB can pass through fabric. SPF concerns tested sunburn protection; UPF concerns the fabric between sunlight and the skin. The terms describe different kinds of protection and should not be treated as interchangeable ratings.

The reference describes how a fabric's weave, color, fit, and condition affect protection. Dense fabric differs from a sheer or loosely woven fabric. Stretching can separate fibers, and wet fabric can let more light through. Coverage matters too: fabric protects the skin it covers. A UPF label does not describe uncovered hands, the face, or gaps in clothing.

Hats, sunglasses, and shade

The FDA's sun-safety guidance describes long sleeves, pants, broad-brimmed hats, sunglasses, and shade alongside sunscreen. It explains that lens darkness does not establish ultraviolet protection. The frame's coverage and the lens's ultraviolet protection are different from its tint.

The FDA also notes that no sunscreen completely blocks ultraviolet radiation. That is why its guidance combines several measures rather than describing sunscreen as a reason to remain outside longer. The UV Index and outdoor days page explains sunlight conditions and shade. The prevention evidence page explains what research has reported about ultraviolet exposure and melanoma.