Sunscreen Explained: How Much SPF Is Enough?

However, if this is hard to follow or all of the extra information stresses you out, just stick with the basics: Use a broad-spectrum SPF 30, applied liberally, every two hours, or after exposure to water. And if keeping your skin smooth, supple, and youthful is of utmost importance, then wear a hat, stay under the beach umbrella, or avoid being outside between 11 a.m. and 3 p.m.—the peak UV exposure hours.

Which is Better: Mineral or Chemical?

Another thing to consider: Whether or not your sunscreen is mineral (or sometimes “physical” or “natural”) or chemical (or some combination of the two). You can usually tell based on whether it absorbs easily into skin (chemical), or leaves a matte, slightly chalky cast atop the skin (mineral/physical).

Chemical ingredients that block UV rays do so by absorbing the rays and neutralizing them, so that they cannot render any harm to your skin cells. These most commonly include avobenzone, octisalate, oxybenzone, and homosalate. These ingredients can be absorbed into the blood stream and are sometimes detected in the blood weeks after applications—hence why some people remain skeptical of chemical SPF applications. Some also are not great for coral reefs (specifically oxybenzone and octinoxate).

Still, similar to using aluminum-packed antiperspirants to counter body odor, people have been using these chemical sunscreen formulas for decades without any severely devastating side effects. If you have to use a sunscreen with a chemical ingredient, avobenzone is probably your best choice, since it offers UVA and UVB broad-spectrum protection. (If there’s one to definitely avoid, it’s oxybenzone.) But that said, mineral options are without question safer all around.

Mineral ingredients sit atop the skin and simply bounce UV rays away, barring entry. These typically include zinc oxide and/or titanium dioxide. Effective formulas leave minimal to no chalky cast on the skin, while low-quality formulas might have you looking like you just powdered your entire face or body.

Most dermatologists will tell you that zinc oxide is the preferred choice between the two, since its coverage of UVA defense is a bit broader than titanium. A 10% zinc oxide base is a really good baseline, too. Both zinc oxide and titanium dioxide are great sunscreens nevertheless, and if you are able to, find a sunscreen with non-nano particles, meaning those particles aren’t small enough to penetrate into your skin (or marine life either).

Water Resistance in Sunscreen, Explained

Many sunscreens are water resistant, but none are actually waterproof entirely. The reason some products don’t list their water resistance, though, is likely because they never paid to have it tested and confirmed. These water-resistance clearance tests are extremely expensive and tedious, which is why many brands go to market without bothering. Plus, the general rule is that you should reapply SPF after any exposure to sweat and water, regardless of water resistance.

The brands that do tout their water resistance are only allowed to list one of two intervals: “up to 40 minutes” and “up to 80 minutes.” Even if they clear 3 hours of sun defense in testing, they can only claim 80 minutes. All of these things are closely monitored for your benefit: The last thing you want is a product that burns your skin and ruins your v