How to Apply Sunscreen the Right Way, According to Derms

Correct application is critical to protecting skin from the sun.

It's common knowledge by now that wearing sunscreen every single day is important; sunscreen, after all, is the best form of protection against skin cancer and other skin damage done by the sun's harmful UV rays. Less obvious is how to apply sunscreen. It may seem like a newbie question with a straightforward answer, but there is actually a right and wrong way to put on sunscreen. And without the right know-how, sunscreen becomes less effective — leaving you vulnerable to wrinkles, sun spots, skin cancer, and more.

The upside is that sunscreen application isn't rocket science and, once you know the tricks, isn't hard to follow. Here's what you need to know.

How Much Sunscreen to Apply

As a general rule of thumb from most dermatologists and the Skin Cancer Foundation, it is recommended that you use approximately one ounce of sunscreen for the body and about a nickel-sized dollop for the face. Together, it's "the equivalent of one shot glass," says Jason Miller, MD, board-certified dermatologist at Schweiger Dermatology Group in Freehold, NJ.

Related:Do You Need SPF for Your Scalp? Here's Everything You Should Know

Don't forget about commonly missed areas, says Hadley King, MD, a New York City-based board-certified dermatologist; these include the hairline, where you part your hair, the neck, the tops of ears, and the backs of hands. Heading to the beach? Don't forget to cover the tops and bottoms of your feet.

How Often Should You Reapply?

You should reapply sunscreen every two hours for both face and body, especially if you're spending time outdoors. You should also slather on another layer immediately after you swim or bathe, as the water might have rinsed most of it off, says Dr. Miller.

FYI: Dr. King also points out that any claims of sunscreens being "sweat-proof" and "waterproof" are no longer allowed by the U.S. Food & Drug Administration. Instead, labels can state "water-resistant" and will typically include on the package after how much time — usually either 40 or 80 minutes — you need to reapply sunscreen.

How Should You Apply Spray-On Sunscreen?

Sunscreen sprays: convenient? Yes. Accurate? Not so much, since quantifying how much sunscreen spray actually reaches your skin can be difficult to see with the naked eye. If you can't quit them, just remember to spray evenly throughout so that skin is covered; Dr. King recommends applying it until you have an even sheen on the skin.

Also worth keeping in mind: You don't want to accidentally inhale your sunscreen, says Dr. Miller. Hold your breath while you apply to stay on the safe side.

Related:How to Find the Right Sunscreen for Oily Skin, According to Dermatologists

How Much SPF Do You Need?

SPF, which stands for sun protection factor, refers to how much UV radiation is required to produce a sunburn on protected skin — e.g. skin with sunscreen on — relative to the amount of solar energy required to produce sunburn on unprotected skin. According to the FDA, the higher the SPF, the better sunburn protection you have.

SPF varies amongst all the sunscreens out in the market. For best sun protection, both Dr. Miller and Dr. King recommend using SPF 30 or higher. However, the benefit does become incremental at a certain point, according to Dr. King, so an SPF 100 isn't significantly better than SPF 50. It doesn't, for instance, offer double the protection.

As important as the SPF itself is, again, the reapplication, which maintains your level of protection. Also, keep in mind: Because the sun's peak exposure usually runs from 10 a.m. to 2 p.m. during the day, says Dr. King, make sure that you're applying sunscreen and wearing sun protective clothing if you can't avoid being out of the sun during those times.

Bottom line: Applying your sunscreen right is important, but so it re-applying it later in the day. It's a worthwhile investment that will pay off for years to come.

Related:What Is Retinol Sunscreen? Why You Should Consider the Skincare Multitasker

For more InStyle news, make sure to sign up for our newsletter!

Read the original article on InStyle.