People choosing sunscreen can be based on the texture, color, brand, and, most importantly, SPF. Nonetheless, some people may have no idea what SPF is. Here is the explanation of SPF.

SPF measures sunscreen protection from UVB rays, the kind that can cause sunburn and contribute to skin cancer. However, SPF does not measure how well a sunscreen will protect from UVA rays, which are also damaging and dangerous.

Dermatologists recommend using SPF 30 or more sunscreen.

First, above SPF 50 (which blocks an estimated 98 percent of UVB rays), the increase in UVB protection is minimal. Second, although UVA protection is also important (UVA not only accelerates skin aging, but also contributes to the initiation of skin cancers), SPF mainly measures UVB protection.

How long does SPF 30 or SPF 50 Protect?

“Tanned skin is damaged skin.” … “Imagine that your skin normally begins to burn after 10 minutes in full sun without any protection. A 30 SPF sunscreen would provide 30 times the protection of no sunscreen.” That means 30 times longer before you start to burn, or in this case, 300 minutes.

SPF — or Sun Protection Factor — is a measure of a sunscreen’s ability to prevent UVB from damaging the skin. Here’s how it works: If it takes 20 minutes for your unprotected skin to start turning red, using an SPF 15 sunscreen theoretically prevents reddening 15 times longer — about five hours.

Which SPF is the best?

SPF 30 is the most common level for most people and skin types. No sunscreen can block all UV rays, but what we do know is: SPF 15 blocks 93% of UVB rays, SPF 30 blocks 97% of UVB rays and SPF 50 blocks 98% of UVB rays.

Can you still get a tan with SPF 30?

“Of course you can still get tan while wearing sunscreen,” Serrador says. … That’s why it’s important to reach for a sunscreen with broad-spectrum UVA/UVB protection. According to the Skin Cancer Foundation, an SPF 15 sunscreen blocks 93 percent of UVB radiation, while an SPF 30 sunscreen blocks nearly 97 percent.

Can sunscreen prevent you from getting darker?

To prevent sunburn and skin darkening, the American Academy of Dermatology recommends all individuals use a water-resistant, broad-spectrum sunscreen that protects against both UVA and UVB rays. Without proper protection, you skin could darken, burn or develop age spots and wrinkles prematurely.

Is there a sunblock that prevents tanning?

Sun block is designed to completely prevent UV rays from getting to your skin; hence the name: sun block. Sunscreen is designed to filter UV rays and prevent sunburn, but will not prevent the production of melanin, meaning that your skin will tan.