The $95 bottle promises "advanced photoprotection." The $13 tube next to it in the drugstore carries the same three-word designation the government makes them both print, "Broad Spectrum SPF," and the same number after it. That is the part the price tag hides. In the United States, sunscreen is a regulated over-the-counter drug, and the numbers that describe protection are not marketing copy. They are test results.

Three claims carry the protection, and the FDA defines each one. SPF is a clinical sunburn test. Broad-spectrum is a lab test for UVA coverage. Water resistance comes in exactly two forms, 40 minutes or 80, each earned by a set immersion protocol, and "waterproof" is banned outright. A brand cannot buy an easier version of those tests. A $200 cream and a supermarket lotion that both read "Broad Spectrum SPF 30, water resistant (80 minutes)" passed the same bar to print it. That bar is the US one. Europe regulates sunscreen as a cosmetic rather than a drug and proves its UVA protection differently, through the UVA-in-a-circle seal and a required ratio of UVA to UVB filtering. Different paperwork, same principle: on both sides the protection claim is a test result, not a price signal.

So back out the price and look at what is doing the work. The active filters are a short, cheap list of the same ingredients. Everything above the drugstore price is the part around them. Dermatologists say this plainly. "Expensive and cheap sunscreens should provide the same degree of sun protection," Dr. Brendan Camp told HuffPost; the expensive one may just be more pleasant to wear. Dr. Melanie Palm, in the same piece, put the markup where it belongs: "Marketing and branding drive up the price of sunscreen, which means expensive doesn't always mean better."

The numbers back the dermatologists. A 2016 study in JAMA Dermatology by Steve Xu and colleagues at Northwestern combed the best-rated sunscreens on Amazon and found people paying up to 3,000 percent more for what was, in protection terms, the same product. This year the same journal ran a UCSF analysis by Maya Mundada, Jeffrey Schneider, and Maria L. Wei comparing three SPF 50 lotions with similar filters. The unit price of that near-identical protection varied up to 17.5-fold. Once you factor in how much skin gets covered by clothing, the cost per use ran wider still, from $0.04 to $3.79. "Less expensive sunscreen, with the same active ingredients and same SPF, is as photoprotective as the more expensive, in terms of protection from UV radiation," Wei said in a UCSF statement.

None of which means the luxury tube is a swindle. What you are paying for is real, it is just not protection. It is texture, a lighter finish, no white cast, and the extras, peptides, hyaluronic acid, antioxidants, a tint that suits more skin tones. That matters more than I once allowed. The best sunscreen is the one you will actually put on and put on again, and if a nicer feel is what gets it onto your face every morning, the feel is not vanity. It is the whole point.

But price cuts the other way too. Higher prices are linked to people using less sunscreen, which is why the UCSF team argued that cheaper options, along with hats and long sleeves, could mean better protection in practice; a thin layer of an expensive filter protects worse than a proper layer of a cheap one. The bigger failure the Xu team found was not price at all: about 40 percent of those top-rated products missed dermatology guidelines, mostly because they were not water resistant. Cost was no shortcut around that, cheap or otherwise. What did track well was the low end, 9 of the 10 cheapest products they looked at met the guidelines. The label is the thing to read, not the price and not the shelf it sits on. SPF 30 or higher, broad-spectrum, water resistant, and then a formula you will not mind reapplying: oil-free if you are prone to breakouts, a mineral one if you react to everything, a tint if the white cast is what stops you. Let your skin pick, not your budget. Ignore the sticker price and the prestige, since on protection the label has already settled it. The only price still worth a glance is the shelf's unit-price tag, the cost per ounce, and that is a question of value, not protection, where the cheap tube almost always wins.