Every year around Memorial Day, health writers across America collectively put on floppy hats and begin reminding everyone to wear sunscreen. Here we are again, participating in the important yearly ritual, but with updated information certainly worth knowing.

Sunscreen advice has been evolving throughout the last few years. The formulas are different thanks to some solid research on ingredients that may not be healthy. Researchers are learning more about UVA damage, visible light, pollution exposure, and skin aging. And despite all the SPF numbers splashed across bottles, independent testing continues to show that many sunscreens do not perform quite as well as their labels suggest.

Meanwhile, despite the yearly reminders, skin cancer rates continue to rise.

The American Cancer Society estimates that more than 100,000 Americans will be diagnosed with melanoma, the deadliest skin cancer, this year, and about 8,000 will die from it. Melanoma rates have roughly tripled since the 1970s. Other less deadly skin cancers have also become incredibly common. In fact, skin cancer remains the most diagnosed cancer in the United States. An estimated one in five Americans will develop skin cancer before age 70.

Most of us understand the need for sunscreen. The problem is that few of us use as much as we should or use it as religiously as we should. Plus, as we learn more about the nature of sun damage and the ways sunscreens work, our personal choices become more complicated and more important.

Sunscreen is one of those areas where details matter. And one of the biggest things dermatologists want people to understand is this: sunscreen is less about finding the “perfect” formula and more about finding one you will use generously and repeatedly. Because sunscreen only works well if enough of it ends up on your skin and you make intelligent decisions about when you are applying and reapplying.

SPF Numbers are Misleading

Here’s where things get a little awkward for sunscreen manufacturers.

Consumer Reports and multiple independent analyses continue to show that SPF labels often overstate real-world protection. Some products perform very well. Others do not. According to Environmental Working Group (EWG) testing, sunscreens delivered an average of just 59% of their labeled UVB protection and only about 24% of the UVA protection implied by their SPF labels. Check your favorite brand at Consumer Reports, EWG, or any credible testing lab site not paid for by sunscreen manufacturers.

The discrepancy in SPF numbers does not mean sunscreen is useless. It means SPF numbers can create a false sense of security, and we need to understand what the numbers really mean.

SPF stands for sun protection factor, and it indicates a sunscreen’s effectiveness against UVB rays, or those that cause sunburn.

Misinformation note: SPF does NOT have anything to do with how long you can stay in the sun. Sunscreen should be reapplied every two hours, regardless of its SPF, and immediately after swimming, sweating, or towel-drying.

According to the American Academy of Dermatology, the magic SPF number is 30. Why? Because it’s clinically proven to block around 97% of UVB rays. While sunscreens with higher SPF do offer slightly more UVB protection, it’s important to note that no sunscreen can provide 100% protection.

An SPF 100 sunscreen is not giving you double the protection of SPF 50. In ideal laboratory conditions, SPF 50 blocks about 98% of UVB rays while SPF 100 blocks about 99%. The difference is surprisingly small.

What matters far more is whether you applied enough, whether you remembered to reapply, and whether the formula provides strong UVA protection in addition to UVB coverage.

UVA vs. UVB: Why “Broad Spectrum” Matters

Ultraviolet rays come in two main forms: UVA and UVB. UVB rays are the ones most responsible for sunburn. They damage the outer layers of skin and are strongly linked to skin cancer.

UVA rays are sneakier. They penetrate deeper into the skin, contributing to wrinkles, sagging, pigmentation changes, and long-term DNA damage. They also pass through clouds and glass, which means you can get meaningful UVA exposure while driving, sitting near windows, or working in bright indoor spaces.

That’s why dermatologists constantly emphasize “broad-spectrum” sunscreen. You want protection against both types of radiation, not just the kind that leaves you red and peeling. Look for the words “broad spectrum” before you buy.

Mineral vs. Chemical Sunscreen

In an era where “clean” skincare is all the rage, the concept of chemical sunscreens get a bad rap. The biggest difference between mineral and chemical sunscreens is how they work.

Mineral sunscreens (sometimes called physical sunscreens) use zinc oxide and titanium dioxide to sit on top of the skin and scatter UV rays.

For years, mineral sunscreens had a reputation for leaving people looking ghostly and vaguely seasick. Anyone old enough to remember thick white zinc on surfers’ noses knows exactly what we mean.

But formulations have improved dramatically. Modern mineral sunscreens are much more cosmetically elegant than they used to be, including newer zinc oxide technologies designed specifically to reduce the infamous white cast on darker skin tones.

Mineral sunscreens tend to be gentler for people with sensitive or acne-prone skin and work immediately after application.

Chemical sunscreens are usually lighter, easier to rub in, less chalky, and often more comfortable for everyday wear and sports. They use ingredients like avobenzone, octisalate, octocrylene, homosalate, and octinoxate that absorb UV radiation and convert it into heat. They also start working from the moment you apply them.

Chemical sunscreens, as a class, are not inherently less healthy. There is an argument that they are healthier because they’re easier to use.

However, chemical sunscreens work by being absorbed into the skin. Absorption means that some of the chemicals may reach the bloodstream and have unintended effects on our bodies and on the environment. Concerns have not been proven, but manufacturers have been quick to pivot away from debatable ingredients.

About Those Chemicals

The good news is that some of the chemicals that have caused the biggest controversies during the last decade have become far less common.

Oxybenzone, which raised concerns because of possible hormone disruption and environmental effects on coral reefs, has sharply declined in use. Octinoxate has also fallen out of favor in many formulations. According to EWG data, oxybenzone was once found in about 70% of non-mineral sunscreens. Now it appears in only a small fraction of products. To be safe, check your sunscreen for these ingredients. If they appear, replace the product. Also, sunscreen doesn’t last forever. If your sunscreen was last used two summers ago, toss it.

The future of chemical sunscreens is looking brighter. Newer, safer ingredients are finally moving toward FDA approval in the United States after years of delay. One of the most talked-about is bemotrizinol, a broad-spectrum UVA and UVB filter already used widely in Europe that appears to provide strong protection with very little skin absorption. Experts believe it could significantly improve the feel and effectiveness of American chemical sunscreens by summer 2027.

Healthy changes in chemical sunscreen formulation is terrific news. Many people simply prefer how they feel.

And that matters. Because the “best” sunscreen is not the one that wins internet arguments. It’s the one you are willing to wear every single day.

You Are Probably Not Using Enough Sunscreen

Are you reapplying a shot glass plus two fingers full of sunscreen several times a day? This is the skin health equivalent of dentists asking whether we floss.

Most adults need about one ounce of sunscreen to cover their bodies adequately. That’s roughly a shot-glass full.

For the face, dermatologists now often recommend the “two-finger rule”: squeeze sunscreen along the full length of your pointer and middle finger, then apply that amount to your face, neck, and ears.

And applying sunscreen is not a once-a-day activity.

It should be reapplied every two hours, and sooner if you are swimming, sweating, toweling off, or spending prolonged time outdoors. When it comes to sunscreen, the words, “water resistant” are somewhat meaningless. Heat and sunlight gradually degrade active ingredients, which means protection fades over time even if you haven’t gone swimming.

Spray sunscreens deserve a quick mention here because they are incredibly convenient and almost universally underapplied or misapplied. If you use a spray sunscreen, you still need enough product to visibly coat the skin, and experts recommend rubbing it in afterward to ensure even coverage. Otherwise, you may end up protecting 14% of your left shoulder and nothing else.

These areas are generally forgotten but critically important:

• tops of ears
• tops of feet
• lips
• scalp
• eyelids
• backs of hands

These are some of the places we are most likely to burn and where dermatologists diagnose skin cancers most often.

Sunscreen Can Always Use Some Help

One more thing worth remembering: hats help. Sunglasses help. Shade helps. Taking breaks from direct midday sun helps. None of this needs to become obsessive or joyless.

Sunshine and fresh air are still two of the best free medicines we have. But healthy sun exposure and reckless sun exposure are not the same thing.

The Bottom Line

The sunscreen conversation has gotten strangely polarized in recent years. Some people now treat chemically based sunscreen as toxic. Others act as though SPF 100 makes them invincible.

The truth, as usual, lives somewhere in the middle.

No sunscreen is perfect. No sunscreen blocks 100% of UV radiation. Some formulas are verifiably better than others. Ingredient concerns are personal but worth considering. And many SPF labels exaggerate how protected we really are.

But the evidence that sunscreen reduces skin damage and lowers skin cancer risk remains very strong.

So don’t panic over the “perfect” sunscreen.

• Find one you like
• Apply more than you think you need
• Reapply more often than you want to
• And wear it often enough that it becomes a boring part of your routine