Sun protection explained: SPF, UVA/UVB and what ‘broad spectrum’ really means

Key takeaways

• SPF measures protection against UVB rays, which are most associated with sunburn.
• SPF alone does not indicate protection from UVA rays.
• Broad-spectrum sunscreens are designed to help protect against both UVA and UVB rays.
• Daily sun exposure adds up over time, even on cloudy days or indoors near windows.

Daily sun protection is one of the most effective ways to help maintain healthy-looking skin, yet the labels can be confusing. SPF numbers, UVA vs. UVB, and "broad-spectrum" claims all play different roles. Here's what they actually mean, and how to use that information to protect your skin every day.

What does SPF mean?

SPF (Sun Protection Factor) measures how well a sunscreen helps protect against UVB rays, the type of ultraviolet radiation most associated with sunburn. For example, SPF 30 allows about 1/30th of UVB rays to reach the skin when applied correctly.

What SPF does not tell you: SPF alone does not indicate protection from UVA rays, which penetrate deeper into the skin and are associated with long-term skin damage and visible aging.

UVA vs. UVB: what's the difference?

• UVB rays primarily affect the surface of the skin and are the main cause of sunburn.
• UVA rays penetrate deeper and contribute to premature skin aging and long-term skin changes.

Because both types affect skin health, protection from both matters.

What does "broad-spectrum" mean?

A sunscreen labeled broad-spectrum is designed to help protect against both UVA and UVB rays. This designation is important because it signals more comprehensive daily sun protection-not just burn prevention.

Why daily sun protection matters (even when it's cloudy)

UV rays can penetrate clouds and windows, meaning everyday exposure adds up over time. Incorporating sunscreen into a daily routine-alongside hats, sunglasses, and shade-helps support overall skin health year-round.

How to use sunscreen effectively

• Apply generously to all exposed skin
• Reapply at least every two hours when outdoors
• Use water-resistant formulas when swimming or sweating
• Pair sunscreen with other protective behaviors for best results, such as wearing long-sleeved shirts, pants, hats and sunglasses

Sun protection you can build into everyday life

Neutrogena® Ultra Sheer® Broad Spectrum Sunscreens

Lightweight, oil-free sunscreens that provide broad-spectrum UVA/UVB protection.

Neutrogena® Hydro Boost SPF Moisturizers

Daily facial moisturizers with broad-spectrum SPF and hydrating ingredients.

Aveeno Protect + Hydrate® Sunscreen

Broad-spectrum sunscreen formulated to help protect skin from the sun while moisturizing.

Frequently asked questions

What does broad-spectrum sunscreen protect against?
Broad-spectrum sunscreen protects against both UVA (aging) and UVB (sunburn) rays.

Is SPF enough to protect my skin every day?
No. SPF measures UVB protection only. Broad-spectrum sunscreen covers UVA and UVB.

Do I need sunscreen if it's cloudy or I'm indoors?
Yes. UV rays pass through clouds and windows, so daily sunscreen helps reduce exposure.