Strolling down the sunscreen aisle at your local drugstore can become overwhelming quickly. There are so many options to choose from. Should you purchase a chemical sunscreen or a mineral sunscreen? Are you opting for a tinted sunscreen that can double as makeup or are you looking for something more sheer? And let’s not forget the question that has left most of us (including me) scratching our heads on more than one occasion: What SPF do you actually need?

We’re finally going to get to the bottom of it. I tapped a few dermatologists to break down what SPF stands for and how to ensure that you’re selecting the best fit for your skin and routine.

What is SPF?

In order to know what level of SPF will best serve you, you first should know what those three letters on the front of your sunscreen tube actually mean. “SPF (Sun Protection Factor) is the protection provided by sunscreen against harmful ultraviolet light that causes sunburns,” says Joel Spitz, M.D., a board-certified dermatologist and co-founder and chief medical officer at Honeydew. “It shows how much exposure to UV light a person using sunscreen can tolerate before getting burned compared to unprotected skin.” That means the number that you see on a tube of sunscreen is telling you the level of ultraviolet light that is being absorbed by the product.

While SPF gives you information about sun protection from UVB rays, Aderonke Obayomi, M.D., M.P.H., F.A.A.D., notes that UVA rays are another story. “SPF only measures UVB protection,” she says. “It says nothing about UVA, which is the wavelength that drives premature aging, dark spots, and hyperpigmentation. That's why the words ‘broad spectrum’ on the [sunscreen] label matter just as much as the [SPF] number itself. Broad spectrum means the sunscreen has been tested and shown to protect against both UVA and UVB.”

What SPF should you be using daily?

Using SPF every day is a must to protect yourself from skin damage caused by the sun, and, according to Dr. Spitz, there is an SPF baseline for daily protection.

“Use a broad-spectrum sunscreen of at least SPF 30 every single day, regardless of the weather,” he says. “Ideally one should build a sunscreen into their daily routine all-year round, especially on weekends or when they are spending more time outdoors at work or play.”

Dr. Obayomi agrees, noting that even when you’re spending time inside, an SPF of at least 30 is necessary. “Daily means every day, including cloudy days, winter days, and days you're mostly indoors near windows,” she says. “UVA rays pass right through cloud cover and glass.”

This also applies to melanated skin. “For my patients of color, this baseline matters just as much,” Dr. Obayomi says. “Melanin offers some natural photoprotection, but it does not prevent UV damage, photoaging, or skin cancer. And UV is one of the biggest triggers for hyperpigmentation and melasma. Daily sunscreen is the single most effective treatment for those concerns.”

Should you ever adjust your SPF coverage?

You may be thinking, “there are so many other SPF numbers other than 30, do I ever need to use those?” and the answer is yes. While SPF 30 provides ample daily protection, there are circumstances in which that alone is not enough.

Increased sun exposure, cosmetic procedures that make your skin particularly vulnerable, and pregnancy hormone changes are just a few cases in which you will want to use a sunscreen with additional protection, says Dr. Obayomi. She also advises using SPF 50 or above for the following common situations:

  • Spending extended time outdoors. Instead of SPF 30, Dr. Obayomi says you should “move up to SPF 50 or higher and reapply every two hours.”
  • You’re around reflective surfaces. “Water, sand, snow, and even concrete bounce UV back at the skin and increase your effective exposure,” she says.
  • At a higher altitude. While you may not have ever thought about it, “UV intensity increases about 10 to 12 percent for every 1,000 meters of elevation,” says Dr. Obayomi, meaning you’ll want additional sun protection.
  • Closer to the equator. “Sun in the tropics is meaningfully stronger than sun at higher latitudes,” she says.
  • Midday hours. “UV peaks between 10 a.m. and 4 p.m., regardless of how warm or cool the air feels,” Dr. Obayomi says.
  • Taking photosensitizing medications. “Certain antibiotics like doxycycline, some blood pressure medications, retinoids, and acne treatments all increase sun sensitivity,” she notes.
  • After in-office procedures. Chemical peels, lasers, microneedling, and active retinoid use leave the skin more vulnerable to UV damage and pigment changes.
  • During pregnancy or hormonal shifts. “These can trigger or worsen melasma,” Dr. Obayomi says. In these cases, you’ll want to use a tinted mineral sunscreen with iron oxide, which “adds visible-light protection that standard sunscreens don't offer,” she notes.

While there are products out there that boast higher numbers like SPF 55 or SPF 70, “SPF 50 is the sweet spot,” says Dr. Spitz. “You don't need to go higher than 50; it gives you broad-spectrum UVA and UVB coverage, and anything beyond that offers only marginal additional benefit.”

How can you determine what SPF will best protect your skin?

“The best sunscreen is the one you'll actually use every day,” says Dr. Obayomi. “Texture, finish, makeup compatibility, and how the formula sits on your specific skin tone all matter, especially for deeper complexions that have historically been underserved by formulas that leave a white cast.”

Beyond that, she says making sure to consider things like family history of skin cancer, skin tone, whether or not you burn easily, skin conditions, climate, and activity level are all important when selecting an SPF. These factors will also help you determine whether you want a spray versus a cream (she says sprays are great for humid climates, while moisturizing creams are great for dry climates), as well as whether to pick a mineral formula over a chemical one.

What’s the difference between mineral and chemical sunscreen?

The main difference between mineral and chemical sunscreens are the ingredients that are providing sun protection. “Mineral sunscreens use the ingredients titanium oxide and zinc oxide,” says Good Housekeeping Institute Beauty & Personal Care Lab Reviews Analyst Chiara Butler. There are more chemical sunscreen ingredients, though you may commonly see a few like avobenzone and octisalate, she says.

“Chemical sunscreens absorb UV light while mineral sunscreens both absorb and scatter UV light, ” Butler adds. Also, the two sunscreen formulations differ in how they appear on the skin. “Chemical sunscreens have a clear appearance on the skin,” Butler says, while mineral sunscreens are likely to leave a white cast due to the mineral particles.

How much sunscreen should you apply?

After you find the SPF that best fits your specific needs, “use about a nickel-sized amount for the face and roughly a shot glass for the body,” Dr. Obayomi says. “Reapply every two hours when you're outdoors, and immediately after swimming, sweating, or towel drying.”