SPF 100 Isn't Twice as Strong as SPF 50 — The Numbers on Your Sunscreen Are More Misleading Than You Think
Most people pick sunscreen the same way they pick horsepower — bigger number, better protection. But SPF doesn't scale the way you'd expect, and the gap between SPF 50 and SPF 100 is much smaller than the labels imply. Here's how the math actually works, and why dermatologists say the number on the bottle is only part of the story.
Mar 13, 2026