Each summer, pharmacies and other retail stores fill their shelves with sunscreen brands who promise: SPF 30, SPF 50, even SPF 100+. Many shoppers reach for the highest number, assuming it offers the best protection. But SPF ratings are only part of the picture — and generally speaking, they give us a false sense of security.
Here’s why SPF isn’t the gold standard we think it is — and what actually matters when protecting your skin from the sun.
What SPF Actually Means (and What It Doesn’t)
SPF stands for Sun Protection Factor, and it’s a measure of how well a sunscreen protects against UVB rays, the kind that cause sunburn. A common myth is that SPF 30 is twice as protective as SPF 15. In reality, the increase is incremental:
- SPF 15 blocks about 93% of UVB rays
- SPF 30 blocks about 97%
- SPF 50 blocks about 98%
- SPF 100 blocks about 99%
That last leap — from SPF 50 to 100 — gives just 1% more UVB protection, yet many consumers believe it offers dramatically more defense. Meanwhile, SPF tells you nothing about UVA rays, which penetrate deeper into the skin and contribute to aging and skin cancer.
The UVA Problem
UVA rays don’t cause sunburn, but they’re no less harmful. They contribute to:
- Premature aging (wrinkles, sagging skin)
- Hyperpigmentation
- Skin cancer (yes, including melanoma)
The trouble is, SPF doesn’t measure UVA protection at all. That means a high-SPF sunscreen will likely still leave your skin vulnerable to long-term damage.
In Europe and Australia, regulations require broad-spectrum protection and often mandate a UVA protection rating. In the U.S., “broad spectrum” is required for marketing, but the UVA bar is relatively low — and rarely is it disclosed clearly for consumers to understand.
The Illusion of Invincibility
High SPF gives many people the illusion that they’re fully protected and don’t need to reapply often. In truth:
- No sunscreen, no matter how high the SPF, lasts all day.
- Sweating, swimming, and simply living your life breaks down protection.
- Most people apply less than half the recommended amount of sunscreen.
So even if you’re using SPF 100, you may only be getting the effect of SPF 30 (or less) in real-world use.
What Should You Look For Instead?
When choosing sunscreen, skip the SPF arms race and focus on these factors:
Broad-spectrum protection – Look for products that clearly state UVA coverage and meet EU standards.
Ingredients that offer stable UVA protection, such as Zinc oxide (mineral, excellent UVA and UVB protection)
Products which indicate Water resistance – Especially important for outdoor activities.
Choose a product that you feel comfortable using. The best sunscreen is the one you’ll actually use regularly. A non-greasy, invisible formula can make all the difference.
Remember to reapply. Regardless of what SPF you start with, you need to reapply every 2 hours, or more often if you’re sweating or swimming.
The Bottom Line
SPF ratings may be useful, but are incomplete at best. They measure only UVB protection, not UVA, and they don’t reflect how real people apply (or forget to reapply) sunscreen. High SPF can create a false sense of security, leading people to overexpose their skin.
The better approach is to choose a balanced sunscreen that protects against both UVA and UVB, feels good on your skin, and fits your lifestyle. Remember: sunscreen is just one part of sun protection. Hats, sunglasses, and shade all matter.
So the next time you’re shopping for sunscreen, ignore the SPF 100 hype, and think about the full spectrum of sun safety.
