SPF 101: Everything You Need to Know About Sunscreen
- Malia English
- Jul 17
- 3 min read
Sunscreen might be the single most important step in any skincare routine — and also the most misunderstood. Between confusing labels, mixed messaging, and "SPF myths" that just won't die, it's no wonder so many people are unsure how to protect their skin properly. Consider this your no-nonsense guide to SPF.
What Does SPF Actually Mean?
SPF stands for Sun Protection Factor, and it measures how well a sunscreen protects your skin from UVB rays — the ones responsible for sunburn and a major contributor to skin cancer risk. Here's the number breakdown:
SPF 15 blocks about 93% of UVB rays
SPF 30 blocks about 97%
SPF 50 blocks about 98%
Notice the jump gets smaller as the number gets bigger. Going from SPF 30 to SPF 50 offers only marginal extra protection — but reapplication matters far more than chasing a higher number.
UVA vs. UVB: Know the Difference
UVB rays cause sunburn and are the main focus of the SPF rating.
UVA rays penetrate deeper into the skin, accelerating fine lines, wrinkles, and sun damage — and they're present year-round, even on cloudy days.
This is why dermatologists recommend a "broad spectrum" sunscreen, which protects against both UVA and UVB rays. If a sunscreen only lists an SPF number without "broad spectrum" on the label, it isn't giving you full protection.
Mineral vs. Chemical Sunscreen
Mineral (physical) sunscreens use ingredients like zinc oxide or titanium dioxide to sit on top of the skin and reflect UV rays. They tend to be gentler for sensitive skin and start working immediately.
Chemical sunscreens absorb UV rays and convert them into heat, which is then released from the skin. They're often lighter in texture and easier to blend, but need about 20 minutes to become effective after application.
Neither is inherently "better" — the best sunscreen is the one you'll actually wear every day.
Common SPF Myths, Debunked
"I have darker skin, so I don't need sunscreen." Everyone's skin can experience UV damage regardless of tone, and everyone benefits from daily protection.
"My makeup has SPF, so I'm covered." Most people don't apply nearly enough foundation or powder to reach the labeled SPF level. Makeup with SPF is a nice bonus — not a substitute for a dedicated sunscreen.
"I only need sunscreen when it's sunny." UVA rays pass through clouds and glass. Daily wear, rain or shine, is what actually protects skin over time.
"One application in the morning is enough." Sunscreen breaks down throughout the day. If you're outdoors, reapplication every two hours is key to staying protected.
How to Actually Wear SPF Every Day
Apply sunscreen as the last step of your morning skincare routine, before makeup.
Use enough product — about a nickel-sized amount for the face alone.
Don't forget often-missed spots: ears, neck, hairline, and the back of the hands.
Reapply if you're spending extended time outside.
Make it non-negotiable, regardless of the weather or season.
The Takeaway
SPF isn't just a summer step — it's a daily habit that protects against premature aging, uneven tone, and long-term skin damage. Whether you prefer a mineral formula or a lightweight chemical sunscreen, the most important factor is consistency.
Looking for personalized guidance on the right SPF and skincare routine for your skin? Our estheticians are here to help you build a routine that actually works for you.