Shopping for sunscreen can feel like a numbers game. With so many options out there—like SPF 30 vs. SPF 50—how can you be sure you’re choosing a sunscreen with enough sun protection for you? Because wearing sunscreen regularly is one of the best ways to protect your skin against signs of premature aging and skin cancer, we want you to be as informed as possible when it comes time to shop.

As it turns out, SPF alone is not the only thing that matters when it comes to sunscreen. “You do want to make sure your sunscreen has an adequate SPF, but there are other things to also to look for when choosing a sunscreen, most importantly that it has broad-spectrum protection to protect against both UVB and UVA rays,” says board-certified dermatologist and LovelySkin CEO Dr. Joel Schlessinger. Follow along as we break down everything you need to know about SPF, including:

• What does SPF mean in sunscreen?
• How do I pick a sunscreen that protects against both UVA and UVB rays?
• Does SPF 50 work better than SPF 30?
• Which can I reapply less often, SPF 30 vs. SPF 50?

What SPF Means in Sunscreen

First, let’s remember that there are two kinds of rays that cause damage to the skin: UVB rays, which cause sunburn, and UVA rays, which cause premature aging. SPF stands for sun protection factor, which is a measurement of how much UVB radiation is needed. “This means that SPF numbers only indicate how much UVB protection a sunscreen provides, so you still have to evaluate each sunscreen for its UVA protection as well,” says Dr. Schlessinger.

What About UVA Protection in Sunscreen?

To make sure your sunscreen protects against UVA as well as UVB, look for the term “broad spectrum.” Sunscreens that are labeled as broad spectrum protect against both burning UVB rays and aging UVA rays. “Because there is no current rating for UVA protection, it’s just a 'yes' or 'no' thing,” Dr. Schlessinger says. “’Yes' can still mean either a resounding ‘yes’ or a weak ‘yes.’ That's why it all comes down to the manufacturer and why I only offer certain sunscreens on LovelySkin.com.”

Do Higher SPF Sunscreens Work Better?

As a sunscreen’s SPF increases, it does block more of the sun’s rays—but that doesn’t necessarily mean that any SPF 50 sunscreen is better than any SPF 30 sunscreen. “It’s not quite that simple,” says board-certified dermatologist and LovelySkin CEO Dr. Joel Schlessinger. “Yes, higher SPF sunscreens do indicate more sun protection in theory—but you might be wondering, how much more?”

When you look at the percentage of protection, there are diminishing returns as SPF numbers go higher and higher. For example, an SPF 15 sunscreen blocks 93% of UVB rays, an SPF 30 sunscreen blocks 96.7 percent of UVB rays and SPF 50 sunscreen blocks 98% of UVB rays. This means there's a bigger difference in sun protection between SPF 15 and SPF 30 sunscreens, but less of a difference when you compare SPF 30 vs. SPF 50 sunscreen.

There are also other factors besides SPF alone that contribute to how well a sunscreen works, including the quality of ingredients. Dr. Schlessinger recommends choosing a sunscreen of SPF 25 or higher that you feel comfortable wearing—that way you’ll be more likely to wear it consistently. “As long as the SPF is above 25, it’s less about the number to me and more about the ingredients and the manufacturer,” Dr. Schlessinger says. “There is a vast difference between manufacturers and the level of ingredients they use as well as the skill they have to produce a cosmetically elegant sunscreen. In order for us to have a sunscreen that our patients want to wear, it is imperative to have a wearable product. That is where the moment of truth occurs.”

Do Higher SPF Sunscreens Last Longer?

According to the American Academy of Dermatology, high-number SPFs do not necessarily last longer than lower-number SPFs, so this doesn’t mean you can spend more time in the sun before reapplying. “There is no sunscreen out there that blocks 100 percent of the sun’s rays,” Dr. Schlessinger says. “That’s why it’s important not only to reapply your sunscreen every two hours, but also to use other sun protection measures such as hats, sunglasses, seeking shade when possible and staying out of the sun during the middle hours of the day when exposure is strongest.”

8 Sunscreens to Try

SkinCeuticals Daily Brightening UV Defense Sunscreen SPF30

This SPF 30 daily facial sunscreen combines beneficial beauty ingredients with broad-spectrum sun protection from a blend of chemical sunscreens (avobenzone, homosalate, octisalate and octocrylene). A trio of brightening ingredients—niacinamide, tranexamic acid and phenylethyl resorcinol—helps reduce skin discoloration with regular use. Glycerin draws moisture into your skin, helping it look plumper, and a touch of mica leaves a subtle shimmer.

La Roche-Posay Anthelios HA Mineral SPF 30 Moisturizer with Hyaluronic Acid

Another fantastic SPF 30 option for face, this all-mineral sunscreen protects against sun damage with titanium dioxide and zinc oxide. Two powerful hydrators, hyaluronic acid and glycerin, combine to bind moisture to your skin’s surface for a soft, fresh-looking finish. This formula also contains Senna alata, a tropical leaf extract with antioxidant properties to help neutralize skin-damaging free radicals.

TiZO Age Defying Sheerfoam Mineral Sunscreen SPF 30

If you’re not a big fan of traditional lotion sunscreens, you’ll love the lightweight mousse texture of this SPF 30 formula with mineral blockers (titanium dioxide and zinc oxide). It comes in both tinted and untinted versions and dries to a matte, silky-feeling finish with no white residue. Vitamins C and E provide antioxidant protection as well, making this facial sunscreen a serious morning multitasker.

EltaMD UV Active Broad-Spectrum SPF 50+

Love to be active outdoors? Protect your body while you work out with this SPF 50 sport sunscreen, which is rated sweat- and water-resistant for eighty minutes of activity. Mineral actives (a combination of zinc oxide and titanium dioxide) make this formula reef-safe, so you can bring it along for your next beach trip. It also contains knotgrass extract to help boost skin’s elasticity and fatty acids to help prevent moisture loss.

Epionce Daily Shield Lotion Tinted SPF 50

This SPF 50 facial lotion has the broad-spectrum protection of a sunscreen with the texture of a primer, making it a natural choice to wear under makeup or in place of a tinted moisturizer. Its sheer universal tint blends flawlessly with most skin tones while zinc oxide and titanium dioxide work together to protect against UVA and UVB rays. A blend of plant-based ingredients—argan oil, apple extract and rice bran—help moisturize skin and leave it feeling soft and smooth.

Colorescience Sunforgettable Total Protection Face Shield Matte SPF 50

Concerned with T-zone shine and large pores? We love this mineral facial sunscreen for oily skin types because it helps cut down on shine by absorbing oil and also minimizes pores with a smooth, matte finish. It contains Colorescience’s own EnviroScreen Technology and zinc oxide to provide broad-spectrum protection against UVA and UVB rays as well as blue light. It’s also water-resistant up to forty minutes, so you can go ahead with that plunge in the pool.

EltaMD UV Clear Broad-Spectrum SPF 46 – Untinted

This facial sunscreen is an all-time favorite of Dr. Schlessinger’s for acne-prone skin. It has a super-lightweight texture and protects skin with transparent zinc oxide—there’s no white cast left behind—as well as octinoxate. It also helps keep skin clear of breakouts and lessens redness with niacinamide and helps plump skin with much-needed moisture thanks to hyaluronic acid.

jane iredale Powder-Me SPF 30 Dry Sunscreen

Looking for any easy way to reapply sunscreen on your face over makeup or on the go throughout the day? This stow-and-go mineral sunscreen powder dispenses through a built-in brush that retracts into its base when you’re done applying it. It offers SPF 30 broad-spectrum sun protection with titanium dioxide and comes in a translucent version as well three different shades.

Planning a trip? Before you pack, you’ll want to see our travel-friendly makeup and skin care suggestions.