When you see SPF, Sun Protection Factor, a measure of how well a sunscreen blocks UVB rays that cause sunburn. Also known as Sun Protection Factor, it's the number you rely on to avoid burning—but it doesn't tell the whole story. Most people think SPF 100 is twice as good as SPF 50. It’s not. SPF 30 blocks about 97% of UVB rays. SPF 50 blocks 98%. SPF 100? Just 99%. That extra 1% isn’t worth the hype, the cost, or the false sense of security.
What SPF doesn’t tell you is anything about UVA rays—the ones that age your skin, cause wrinkles, and contribute to skin cancer. That’s where broad-spectrum, a label meaning the sunscreen protects against both UVA and UVB radiation comes in. Without it, you’re only half-protected. And even then, sunscreen wears off. Sweat, water, rubbing your face with a towel—each of these strips away protection. Reapplying every two hours isn’t a suggestion; it’s a rule. If you’re outside all day, you’re not just applying sunscreen once in the morning. You’re reapplying like clockwork.
People often skip sunscreen because they think they’re not at risk. But UV damage adds up over time. You don’t need a beach day to get burned. Driving in the car? Your left arm and face get more sun than you realize. Working near a window? UVA rays pass through glass. Even on cloudy days, up to 80% of UV radiation hits your skin. That’s why daily sunscreen use, the practice of applying sunscreen every day, regardless of weather or plans is the most effective way to prevent premature aging and reduce skin cancer risk.
There’s no magic number that makes you safe. SPF 15 is enough for short indoor exposure. SPF 30 is the sweet spot for daily outdoor use. SPF 50+ is useful for long days in direct sun, but only if you apply enough—most people use half the amount needed. And forget the idea that higher SPF lets you stay out longer. No sunscreen gives you all-day protection. It’s not a force field. It’s a tool. And like any tool, it only works if you use it right.
What you’ll find below are real, practical guides on how sun protection works in everyday life—from how to pick the right product, to what happens when you mix sunscreen with other skincare, to why some people still burn even with SPF 50. These aren’t theory pieces. They’re based on what people actually experience, what doctors recommend, and what the science shows when you cut through the marketing noise. Whether you’re worried about aging, skin cancer, or just not wanting to peel after a weekend outside, the answers are here.
