Sunscreen basics: SPF, broad spectrum and water resistance

If the goal is to look good in the sun without damaging your skin, sunscreen does far more than any tanning product. Here's how to read the label, based on FDA: Sunscreen: How to Help Protect Your Skin from the Sun and AAD: How to read sunscreen labels.

SPF

SPF (sun protection factor) measures how well a sunscreen protects against sunburn, which is caused mainly by UVB rays. A higher SPF means more protection against burning, but no sunscreen blocks all UV. Dermatologists generally recommend SPF 30 or higher.

Broad spectrum

"Broad spectrum" on a U.S. label means the product passed the FDA's test for protection against both UVA and UVB. UVA rays penetrate deeper and contribute to skin aging and skin cancer. Choose broad spectrum.

Water resistance

Under FDA rules, "water resistant" claims must state a time, 40 or 80 minutes, of swimming or sweating. Sunscreens can't be labeled "waterproof" or "sweatproof." Reapply after swimming, sweating or towel drying.

How to apply it

• Apply before going outside, to all exposed skin, including the ears, the back of the neck and the tops of the feet.
• Most adults need about an ounce (roughly a shot-glass amount) to cover the body.
• Reapply at least every two hours, and more often after swimming or sweating.
• Use it alongside shade, hats, sunglasses and protective clothing, especially at midday.

Sunscreen and self-tanner

A sunless tan from a DHA lotion or spray isn't sun protection. You still need sunscreen. See sunless tanning alternatives.

Related: tanning beds and UV · ABCDE mole check

Published October 25, 2026. Sources are linked in the text. See our Medical Disclaimer.