What the SPF in Your Sunscreen Means

Even with the simplest skin care routine, sunscreen is the one product you should never leave home without. Dermatologists like Melissa Piliang, MD, recommend wearing sunscreen every day.

But what is the best sunscreen? And which SPF should you buy? Before you head to the store, let’s answer these (and other) burning questions.

How does sunscreen work?

Sunscreens come in gels, creams, powders and sprays that you apply directly to your skin. The active ingredients in sunscreen work to filter out the ultraviolet (UV) rays before they’re absorbed and cause any skin damage.

UV rays — which come from the sun, tanning beds and indoor fluorescent lighting — can cause skin cancer and other signs of aging like wrinkles, dark spots and sagging.

“Regular sunscreen use reduces and prevents these effects,” says Dr. Piliang.

What is SPF?

The sun protection factor (SPF) listed on sunscreen labels is an important piece of information. SPF tells you how much protection you’re getting from UVB (ultraviolet B radiation) rays and sunburn. The lower the SPF, the less protection you have. So, a sunscreen with SPF 15 offers more protection than SPF 8. And SPF 30 gives you 30 times more protection than if you didn’t wear any sunscreen at all.

“For days when you’re outside for only short periods, you can get away with a minimum of SPF 15,” notes Dr. Piliang. “But if you’re going to be outside for more than a few minutes, choose at least SPF 30.”

Choosing the best sunscreen for you

Although higher SPFs offer more protection from UVB rays, they don’t offer any protection from UVA (ultraviolet A radiation) rays. That’s why you’ll want to look for broad-spectrum sunscreens that can protect you from both. And while there’s ongoing debate on whether mineral or chemical sunscreens are better for you, it’s best to avoid aerosol sunscreens, as several have been recalled in recent years because of benzene contamination.

What SPF do you need?

Studies have shown that SPF 100 sunscreens provide the most protection, but they can also give you a false sense of security if you’re not using it enough or in all the right places. Any broad-spectrum sunscreen with an SPF of 15 or higher can offer you a good amount of protection as long as you reapply it:

• After swimming
• At least once every two hours when you’re out in the sun

The reason? Factors like sweat and water can make your sunscreen wear off faster.

“Daily use of sunscreen that’s SPF 15 or higher can reduce your risk of melanoma, the deadliest form of skin cancer, by 50%,” stresses Dr. Piliang. “It can also decrease your risk of the most common skin cancer, squamous cell carcinoma, by 40%.”

Also, check that you’re not using expired sunscreen or sunscreen that’s been stored improperly — these can make your sunscreen’s SPF less effective. And remember, SPF isn’t the only thing that can protect you from the sun.

“No sunscreen can block all UV rays,” clarifies Dr. Piliang. “Good sun protection should also include seeking shade and wearing sun-protective clothing, wide-brimmed hats and sunglasses. Enjoy the sun — but be smart about how much exposure you’re getting.”