For most people, SPF 30 is the right starting point. The American Academy of Dermatology recommends everyone use a broad-spectrum, water-resistant sunscreen with SPF 30 or higher whenever exposed skin will be outside. SPF 30 blocks 97% of the sun’s UVB rays, which is enough protection for daily life and most outdoor activities.
What the SPF Numbers Actually Mean
SPF measures how much UVB radiation (the type that causes sunburn) your sunscreen filters before it reaches your skin. The numbers climb steeply at first, then flatten out. SPF 30 blocks 97% of UVB rays. SPF 50 blocks 98%. SPF 100 blocks 99%. That means jumping from SPF 30 to SPF 50 gains you just one additional percentage point of protection, and doubling again to SPF 100 adds only one more.
This doesn’t mean higher SPFs are pointless. That extra 1% matters more than it sounds for people who burn easily, spend hours outside, or tend to apply too little sunscreen. But it does mean that SPF 30 applied properly gives you the vast majority of available UVB protection, and going above SPF 50 offers diminishing returns.
Why “Broad Spectrum” Matters as Much as SPF
SPF only measures protection against UVB rays, which cause sunburn and surface-level skin damage. It tells you nothing about UVA rays, which penetrate deeper and are responsible for premature aging, wrinkles, and pigmentation changes. UVA radiation also contributes to skin cancer risk.
To get UVA protection, look for the words “broad spectrum” on the label. In the U.S., the FDA requires sunscreens labeled broad spectrum to pass a specific test proving they absorb UVA wavelengths up to at least 370 nanometers. Without that label, your sunscreen may leave your skin exposed to UVA damage even while preventing sunburn. If you’re shopping for sunscreen sold in Asian markets, you’ll see a separate PA rating (marked with plus signs) that specifically measures UVA protection. The more plus signs, the better.
SPF Recommendations by Skin Tone
Your skin’s natural melanin level affects how quickly you burn, which influences your minimum SPF needs. Dermatologists often use a six-point scale based on how skin responds to sun exposure:
- Very fair to medium skin (types I through IV): These skin tones range from ivory to olive and include anyone who burns easily or moderately. SPF 30 or higher is recommended for everyday use.
- Dark brown to deeply pigmented skin (types V and VI): These skin tones rarely or never burn. SPF 15 or higher daily is the minimum recommendation, though SPF 30 still offers a meaningful buffer against UV damage and hyperpigmentation.
Darker skin does offer more natural UV protection, but it doesn’t make you immune to sun damage or skin cancer. UVA rays in particular can cause uneven skin tone and dark spots in all skin types.
How Much to Apply (and How Often)
The SPF rating on the bottle assumes you’re applying a specific amount: two milligrams per square centimeter of skin. In practical terms, that works out to about a shot glass (two tablespoons) for your entire exposed body and a nickel-sized dollop for your face alone. Most people apply roughly a quarter to half of what’s needed, which means your SPF 30 may effectively function more like SPF 10 or 15.
This is actually the strongest argument for choosing a higher SPF. If you know you tend to apply a thin layer, an SPF 50 applied at half thickness still gives you more real-world protection than an SPF 30 applied the same way.
Reapply every two hours when you’re outdoors, and immediately after swimming or heavy sweating. Water-resistant sunscreens hold up better during activity, but no sunscreen is waterproof. The label will tell you whether it maintains its SPF for 40 or 80 minutes of water exposure, after which you need to reapply.
SPF in Makeup Is Not Enough
Foundations, BB creams, and tinted moisturizers often advertise SPF 15 or SPF 30 on the packaging, which sounds reassuring. The problem is the concentration of sun-protective ingredients. A dedicated sunscreen typically contains 15% to 20% or more active UV filters. A foundation with SPF claims often contains around 1% of the actual sun-blocking ingredient. The American Academy of Dermatology has stated directly that SPF makeup alone doesn’t provide adequate protection.
If you want both coverage and sun protection, apply a full layer of standalone sunscreen first and let it absorb, then layer your makeup on top. Tinted sunscreens are a good compromise: they’re formulated as actual sunscreens with cosmetic tinting added, so the UV filter concentration matches what’s on the label. The AAD specifically recommends tinted broad-spectrum sunscreens with SPF 30 or higher for protection against both UV and visible light.
Choosing the Right SPF for Your Situation
For a quick framework: SPF 30 broad spectrum covers most daily situations well. If you’re spending extended time outdoors, at the beach, hiking, or working outside, SPF 50 provides a practical safety margin, especially since most people under-apply. Going above SPF 50 is reasonable for very fair skin, high-altitude activities, or tropical sun, but the additional protection is marginal compared to simply reapplying on time and using enough product.
Don’t forget your lips. A lip balm with SPF 30 or higher protects an area that burns easily and is often overlooked. For children six months and older, the same SPF 30 broad-spectrum recommendation applies. For babies under six months, shade and protective clothing are preferred over sunscreen.
The SPF number matters less than consistency. A sunscreen you’ll actually wear every day, applied generously and reapplied when needed, will always outperform a higher-SPF product sitting in your medicine cabinet.