If you keep up with the dos and don'ts of skin care, you likely know how essential SPF is to your daily routine. But have you heard of the two-finger method? It's a means of applying SPF and, as you'll learn, proper usage is a huge part of measuring whether sunscreen is effective and serving its purpose as you wear it.

What's more, research shows that most people are misunderstanding the correct method. A 2014 study found that overall, consumers only use about 20 to 50% of the amount of sunscreen needed to achieve the numbered protection on the bottle.1 Surprised? Read on to learn the correct way to apply SPF and the best sunscreens to work into your routine, according to dermatologists.

What Are the Benefits of Sunscreen?

Simply put, "sunscreens reflect the UV rays of the sun," explains dermatologist Michael I. Jacobs.

Wearing sunscreen has many other benefits, too, some of which may actually surprise you. Here are just a few of the main ways that a good SPF can improve the condition of your skin:

• Evens skin tone
• Protects against sunburn
• Helps with hyperpigmentation
• Slows and prevents premature aging (wrinkles, dark spots)
• Prevents skin inflammation
• Lowers risk of skin cancer2

A major reason that sunscreen has such a long list of benefits is that the sun itself can harm our skin in just as many ways. "Sunscreen is the onlytopical that gives proven protection against the harmful effects of the UV rays on our skin," esthetician Okikiola Asher explains. "As we all know, sun damage is the [number] one enemy of our skin. To guide against melanoma, photo-aging, and hyperpigmentation, the use of sunscreen is highly essential.” Besides sunscreen, you can also use sun protective clothing, hats, sunglasses, and seeking shades as supplementary methods that offer proven sun protection.

According to Asher, those on a skincare budget should dedicate 40% of it to a good sunscreen, as well as give it a prominent place in your daily routine. “Sunscreen application should be the last step of your skincare routine during the day (after your moisturizer)," she explains. "If you are wearing makeup, sunscreen comes before your foundation.”

How to Effectively Apply SPF

The two-finger method is an easy way for you to measure how much sunscreen should be applied on your face. To try this technique, simply squeeze the product in two separate lines on your pointer and middle finger. “For maximum coverage, the sunscreen protection factor has to be SPF 30 and above," Asher says. Also, be sure to add product in proportion to the amount of skin that will be exposed to the sun: "I generally advise sunscreen to be applied to the exposed parts of the body. Face, arms, and legs as the case may be, since our face is always in direct contact with the sun."

Unlike some skincare steps, sunscreen usually needs multiple applications a day, especially if you're spending a lot of time outside. “The potency of the sunscreen breaks down on the skin as it interacts with body oils and fluids," Asher explains. "Therefore, reapplication is required every two hours.” 

Dermatologist Sam Bunting echoes this, saying, "Just like painting a wall, you want an even layer all over the skin— always reapply it every 120 minutes when in direct sunlight."

How Much Sunscreen You Need

According to Bunting, you'll need "more than you might think."

"You need 2 milligrams per square centimeter of the body," Bunting elaborates. "That translates to a quarter of a teaspoon for the face and a shot glass amount (30 ml) for the whole body." Dr. Jacobs offers a similar estimate: "The correct amount of sunscreen to apply is about one ounce, enough to cover the entire exposed skin. Sunscreen should be applied every two hours when outdoors, with an extra application after swimming or sweating from sports."

Dr. Bunting repeats Asher's instruction that sun protection should always be the final step in your skincare routine, "even if you plan to wear foundation that contains an SPF."

When to Apply

No matter the season or weather, ultraviolet rays are at work. Sunscreen should be worn every single day, year-round. “Unless you live in a basement where there is no trace of sunlight, wear sunscreen indoors because sunlight can seep through your windows and blinds,” Asher explains.

Rain or shine, we should maintain implementing SPF in our lifestyle and regimen. Asher shares, “Sunscreen isn’t seasonal; it should be used throughout the year with the same commitment. I know it’s not that easy, especially for those who wear makeup every day. The easiest way to master reapplication is getting a spray sunscreen. I also encourage my clients to set a timer or alarm for reapplication.”

The Proper SPF

The most important thing with sunscreen is to apply the correct dose. The American Academy of Dermatology recommends using a broad-spectrum sunscreen of 30 SPF (or higher) daily.3

"The SPF factor is only guaranteed if you apply enough," says Dr. Bunting. And while you might think that using an SPF of 50 or 100 will last you longer or doesn't call for using the same amount of product, that is simply not the case. Whichever SPF factor you're using, you need to apply and reapply as instructed.

The Takeaway

It's common knowledge that SPF is necessary protection, but it's safe to say that most of us are guilty of not using an adequate amount, forgetting to reapply, or skipping days altogether. However, reminders of the benefits of preventive skincare are enough to encourage almost anyone to slather on SPF regularly. Our skin can’t handle unfiltered exposure from the sun, and at-home solutions can’t compare to clinically approved sunscreen. (Carrot oil, shea butter, and coconut oil will not provide sufficient sun protection, according to Asher.) But, the two-finger rule and reapplication every two hours will do wonders for your skin, especially in the long run. You may not notice a huge difference when you're actively wearing sunscreen, but future you will thank younger you for less wrinkles, more even skin, and more benefits.