The Sunscreen Glossary

An oil-soluble ingredient that protects against both UVA and UVB rays. Often combined with octocrylene to stabilize the formula, it is only effective for about 30 minutes. Try to avoid using sunscreens with this ingredient.

Broad spectrum is the ideal sun protection, providing protection from both UVA and UVB rays which is essential when protecting against sunburn and the damage rays can wreak internally.

One of two kinds of sunscreen (in addition to Physical Sunscreens, below), this formulation contains organic compounds such as oxybenzone and octinoxate which absorb into the dermis, essentially absorbing the sun’s UV rays as they attempt to penetrate the skin barrier. These sunscreens are historically more popular because they have a silkier, more easy-to-absorb texture than Physical Sunscreens and come in mists and sprays for easy application.

The EWG (Environmental Working Group) recommends avoiding certain common ingredients found in chemical sunscreens–oxybenzone, octinoxate, homosalate, octisalate, retinyl palmitate–because of the possibility that they may be hormone disruptors. Our takeaway? Read labels and do research, and find a formulation that delivers ingredients that you are comfortable with.

The FDA mandates that all sunscreens remain at their original strengths for three years, after which it is best to toss out. Most sunscreens have expiration dates on their bottles, but if they don’t, we recommend writing the date of purchase right on the bottle. To keep sunscreen at peak performance, be sure to store it in cool places where the bottle is not exposed to sunlight for prolonged periods of time.

One of two kinds of sunscreens (in addition to chemical sunscreens, above), this formulation contains active mineral ingredients such as zinc oxide and titanium dioxide which causes the formula to essentially sits on top of your skin, deflecting UV damage away from the dermis. They have a reputation for not rubbing into skin as well as chemical sunscreens, but they are the most recommended formulas by dermatologists and are also great for sensitive skin types because they are non-irritating, non-allergic, and non-comedogenic.

From oils and mists, to setting powders and clear gels, there is a growing wave of newfangled sunscreen formulations. Their modernized feel and seamless appearance (the invisible formulas are especially favorable for darker skin tones as they sidestep the usual chalky finish) are big selling points, and if they have an adequate level of SPF, their efficacy is entirely comparable to their traditional counterparts. The thing to remember, especially with mists, is that upon application (especially at the beach) a lot of the spray never makes contact with your skin. This is a waste, for one, but it also can lend the impression that you are protected when you may not be. When using sprays, try to get close to the skin and spray in sections while rubbing and distributing.

This is the concept that for most adult bodies, you need the equivalent of one shot glass of sunscreen to adequately cover your entire body (and a half a teaspoon for your face).That being said, less is not more, here.

Stands for Sun Protection Factor, or the measure of how well you’re protected from UVB rays. The higher the number SPF, the better protection the sunscreen provides (to a point, see below). Something to note is that SPF only refers to protection factor from UVB rays, but not UVA. Look for sunscreens that also include the verbiage “broad spectrum” (see definition, above).

A note on SPF strength: At some point, SPF effectiveness starts to level off as the number rises, so many dermatologists suggest SPF 30 for daily use with light sun exposure, and SPF 50 for extended periods of time outdoors. According to dermatologist Dr. Sonia Batra, “As general rule, SPF 15 protects against 94% of rays, an SPF 30 is a 97% block, and an SPF 50 is a 98% block so for most of us the benefits start to plateau.”

It works. You should wear it. Remember, there are flaws when it comes to SPF application (especially when done solo or with sprays), so sun-protective hats, tops, and even bathing suits are a great way to boost your coverage. Actually, you should just always wear a hat no matter what.

This is an ingredient used in mineral sunscreens to shield against and absorb skin-damaging, cancer-causing UV light. Because the particle size is so small, it is used in cosmetic sunscreens to provide a transparent barrier against visible UVA/UVB damage. It is also FDA-approved safe to use on infants aged 6+ months and children.

Sunlight has many different kinds of “rays”, but the ultraviolet rays are the most damaging to our skin, causing skin to age and potentially cause skin cancers. UVA and UVB rays are the two most basic types of ultraviolet rays that can reach the earth's surface and penetrate your skin. 

Fun fact: There are over 500x more UVA rays in sunlight than UVB rays. While typical sunscreens protect against UVB rays, many do not protect against UVA rays, so it is essential to find a sunscreen that protects against both.

UVA rays are longer than UVB rays and penetrate the deepest into the dermis, making them one of the greatest factors in premature aging of the skin, including wrinkle formation AKA photoaging. These rays also play a role in sunburn, though not as much as UVB rays.

UVB rays are the ultraviolet rays that reach the earth’s surface and are most responsible for causing sunburn. These types of rays also play the greatest role in causing skin cancers.

Cities in the United States are given numbers between 0 and 15 that rate the strength of present ultraviolet rays. Cities between 0 and 2 are considered the lowest risk with an estimated “minutes to burn” at 60 minutes. Cities numbered between 10 and 15 are considered high risk with an estimated “minutes to burn” at 10 minutes. Find your area’s UV Ray Index through the  National Weather Service. 

Formulas who boast this ability have to pass intense water emergence testing prior to their SPF testing, so you can trust that these products will be effective under water. The key thing to remember here is to reapply after you get out of the water. Many brands say protection lasts for 80 minutes, but at a minimum, re-apply every hour. Again, less is not more when it comes to sunscreen.

Regular or micronized (a smaller particle size), zinc oxide is the most common ingredient in mineral sunscreens and provides broad-spectrum sun protection, protection from skin cancer, and aids in the recovery of sunburns.