How Much Sunscreen Do You Really Need to Apply Every Day?
Getty Images
When you buy a sunscreen that says SPF 30 on the packaging, you probably assume it's going to give you SPF 30 protection. And it will—conditionally. Everything you need for skin that’s well-protected from the sun is inside any chemical or mineral sunscreen with a higher sun protection factor, but ultimately, how well your skin is defended from sun damage depends heavily on applying—and reapplying—enough of your chosen formula.
And if we're being completely honest with ourselves, very few of us are actually applying enough every day.
"To get the protection labeled on the product, you would need to replicate the application they do in the lab, which is two milligrams per square centimeter for the average person. That translates to half a teaspoon on face and neck combined—a quarter teaspoon each—and one teaspoon per arm and leg each, front and back," says board-certified dermatologist Ranella Hirsch, MD. "Realistically, people use somewhere around half of that amount."
Needless to say, we could all use a reminder about how much broad-spectrum sunscreen to use and why. Here's what the experts have to say about application, reapplication, and all of the variables that come into play, like SPF level, being indoors, and more.
Meet the experts:
Ranella Hirsch, MD, is a board-certified dermatologist in Cambridge, Massachusetts.
Roberta Del Campo, MD, is a board-certified dermatologist in Miami.
Marisa Garshick, MD, is a board-certified dermatologist in New York City.
Mary Lupo, MD, is a board-certified dermatologist in New Orleans.
Azadeh Shirazi, MD, is a board-certified dermatologist in La Jolla, California.
Carolyn Stull, MD, is a board-certified dermatologist in New York City.
Ellen Marmur, MD, is a board-certified dermatologist in New York City and the founder of MMSkincare.
How much sunscreen should you use on your face?
You’ve probably heard the rule of thumb, or rather, the two-finger rule about how much sunscreen you should be applying. Board-certified dermatologist Marisa Garshick, MD, recommends applying a nickel-sized dollop of sunscreen to the face and neck. That’s equivalent to about half a teaspoon—or two finger lengths.
She goes on to explain that applying this amount is key to getting the level of protection indicated by the label on your sunscreen bottle, regardless of the formula (mineral or chemical), your location, or what time of year it may be.
How much sunscreen should you use on your body?
Every board-certified dermatologist we asked, including Dr. Garshick, said the same thing about the amount of sunscreen you should be using: To achieve the SPF labeled on a sunscreen bottle, it is recommended to use two milligrams of sunscreen per square centimeter of skin. That adds up to about two tablespoons, or a shot glass’s worth, for the entire body Dr. Garshick clarifies.
If you're reluctant to slather on a lot of sunscreen lest you get the dreaded white cast, choose a sunscreen with a higher SPF number. "The increased level of protection compensates, to an extent, for under-application," says Dr. Hirsch. However, "this does not negate the need to reapply after two hours for sweating or swimming or being outdoors, which is one issue with the super high SPFs—people tend to think they are 'one and done' for application, which is not correct."
With lotion—we love Allure Readers’ Choice Award winner Supergoop Glowscreen Body SPF 40 for a chemical option and Best of Beauty Award winner Avène Mineral Sunscreen Face & Body Lotion SPF 50 for a mineral option—it’s easy to assess how much you’re applying. But for the types of sunscreen that can’t be squeezed into a shot glass or drizzled onto your fingers, you'll have to rely on other techniques to ensure you're applying enough. "For stick sunscreens, it's best to apply four passes back and forth and then massage it for even coverage," Dr. Garshick says. One of our favorites is the Allure Best of Beauty Award-winning Shiseido Clear Sunscreen Stick SPF 50+.
For sunscreen mists, Dr. Garshick recommends spraying enough on your skin that it's shining after you rub it in. "I always tell patients, 'If it's glistening, then you're listening.'" We're big fans of Bask Non-Aerosol Invisible Mist Sunscreen SPF 50, which sprays easily from every angle and feels like you’re wearing practically nothing.
Eau Thermale Avène Mineral Sunscreen Face & Body Lotion SPF 50
$38.00, Amazon
Shiseido Clear Sunscreen Stick SPF 50+
$32.00, Amazon
Bask Non-Aerosol Invisible Mist Sunscreen SPF 50
$24.00, Nordstrom
What SPF should you use?
You'll be hard-pressed to find a dermatologist who will tell you anything under SPF 30 is sufficient—even with diligent application—to truly protect skin from discoloration, collagen breakdown, and skin cancer.
Dr. Hirsch says there’s still a common misconception that there’s very little difference between SPF 30 and SPF 50, but “there is a meaningful difference.” Specifically, when you wear SPF 30, 1.5 times more UV is getting through the filter. Therefore, she recommends a minimum of SPF 50 for both face and body when you’re outside.
In addition to seeking out a high SPF number, make sure your sunscreen is labeled “broad-spectrum.” That means it protects against both UVB and UVA rays.
When should you use sunscreen?
It may sound silly, but unless it’s nighttime and you’re in bed, sleeping, you should probably wear sunscreen.
“No matter the time of year, the sun is always emitting harmful UV rays,” says board-certified dermatologist Mary Lupo, MD. “Even though you may not receive a sunburn in colder months, it’s important to keep the skin protected year round as these rays can cause premature aging and DNA damage.”
DNA damage, which can lead to skin cancer, is specifically caused by UVB rays. “They are highest in intensity between 10 A.M. and 4 P.M.,” says board-certified dermatologist Carolyn Stull, MD. UVA rays, on the other hand, “are present throughout the day and penetrate more deeply in the skin, causing damage to collagen and elastin and leading to photodamage.”
If you're inside most of the day and anywhere near a window, that window may block UVB rays, but it won't block UVA rays. Board-certified dermatologist Azadeh Shirazi, MD, says to make indoor application a habit. "After all, we all go outside to check the mail, walk the dog, and sit next to a window. Over time, this accumulation of UV radiation takes a toll on the health and appearance of our skin."
And remember, you're not just protecting yourself against skin damage caused by UVA rays when you're indoors. "While the majority of blue light exposure is from the sun, our digital devices emit high energy visible light, and some sunscreens may offer protection against this," Dr. Garshick says.
How often should you reapply your sunscreen?
In a word: very. "Reapply every two hours at a minimum but more often if sweating or immersed in water," board-certified dermatologist Roberta Del Campo, MD, tells Allure, echoing the recommended reapplication frequency of every expert we spoke to. This is true for sunscreen that claims to be water-resistant, too.
But does that mean you have to strip down and reapply sunscreen all over your body every two hours? Not necessarily. Dr. Garshick says clothing may provide some degree of protection—a white cotton T-shirt, for example, offers a UPF (ultraviolet protection factor) of five—so how long you'll be outside and the type of exposure would determine the need to reapply sunscreen underneath clothing. "If you will be in direct sun exposure or spending a significant time outdoors or at the beach, it is best to wear UPF clothing to provide an extra degree of protection," she says.
The next best thing, according to Dr. Del Campo, is clothing with a high thread count. "Clothing that has tight thread knitting protects best if it's not UPF-enhanced clothing," she says. "I always recommend a layer of sunscreen under clothing with high amounts of sun exposure, but I do not necessarily recommend reapplying under clothing as the sunscreen doesn't break down as quickly without direct sunlight or excessive sweating."
However, since certain body parts other than your face aren't covered by clothing, Dr. Garshick says those particular areas definitely need sunscreen reapplication. "It is important to remember to reapply to the scalp, hands, neck, ears, lips, tops of feet, and areas that may be exposed that you may not realize," she says.
And yes, reapplication is important indoors, too—especially if you spend any amount of time in a room with natural light. "If it is light enough for you to see, that is sun," says Dr. Hirsch. "If you are indoors all day and not near any direct sunlight, reapplying doesn't have the same urgency. But if you sit, as many people do, at a desk facing a window with sunlight pouring in, you should really think about that, because UVA goes through glass."
Is using makeup with SPF enough sun protection?
Makeup with SPF is well-intentioned, and it definitely can’t hurt in your pursuit of protection, but you shouldn’t rely on it as your only line of sun defense for your face. While some makeup meets the criteria of a minimum SPF of 30, “It is not clear how much of the product needs to be applied to reach the SPF on the label,” Dr. Stull says.
Your best bet: Regardless of skin type, apply an actual sunscreen at the end of your skin-care routine, before you apply your makeup, regardless of that makeup’s SPF level. “I would never skip applying a general SPF beforehand," board-certified dermatologist Ellen Marmur, MD, says. “UV rays are extremely powerful, and depending on the climate, makeup can fade throughout the day, so it’s better to double up.”
A final word
Sunscreen is arguably your most important skin-care product, but Dr. Garshick says to not forget that it’s just one piece of the sun-protection puzzle. "It is also important to remember other sun-protective strategies," she says, "including seeking shade, wearing a wide-brimmed hat and sun-protective clothing, and avoiding peak hours of UV exposure."
Keeping up these good, consistent sunscreen habits can make an enormous difference over the years, not only in your appearance but in your health. And that’s worth what may initially feel like an inconvenience.
More on SPF:
Now check out 100 years of sun care:
Follow Allure on Instagram or subscribe to our newsletter for daily beauty stories delivered right to your inbox.
Originally Appeared on Allure
