June 3, 2021

How SPF ratings work

If you're uncertain about what the SPF number stands for in your sunscreen, you're not alone. The aestheticians at Jeune Skin Care explain the rating system.

The Sun Protection Factor system (SPF) measures the length of time a sunscreen will protect your skin from burning and becoming red from the UVB rays, compared to how long it would take your skin to burn without any sunscreen protection.

To determine the protection level of a sunscreen, multiply the SPF rating by the amount of time it takes your skin to develop burning/red from the sun. This will vary from person to person.

If it takes 10 minutes without any sun protection for your skin to begin reddening, using an SPF 15 would theoretically prevent reddening 15 times longer (10 x 15 = 150); 150 minutes or 2 ½ hours.

Using an SPF 30 would give 30 times longer (10 x 30 = 300); 300 minutes or 5 hours.

To maintain SPF, reapply sunscreen every 2 hours (even with high SPF) and right after swimming. The Skin Cancer Foundation recommends SPF of at least 15, which blocks 93% of UVB rays. While SPFs higher than 30 blocks only 4% more UVB, it may be advisable for sun-sensitive individuals, skin cancer patients, and people at high risk for developing skin cancer.

Remember that the current rating system only applies to UVB rays. It is important to find a "broad-spectrum sunscreen," meaning it shields against most UVA rays as well as UVB rays. Look on the label for these UVA protecting ingredients:

  • Zinc oxide

  • Titanium oxide

  • Avobenzone

To sum it up, it is best to find a broad-spectrum SPF of 15 or greater and reapply every 2 hours.

Jeune Skin Care

Jeune Skin Care is a unique service staffed by licensed aestheticians who can help determine what products can best fit your skin care needs. Among the broad-spectrum sunscreen products available at Jeune:

  • OBAGI Matte SPF 50 - $53.00

  • Revision Intellishade SPF 45 Original - $75.00

  • Revision Intellishade SPF 45 Matte - $75.00

  • SkinCeuticals Physical UV Defense SPF 30 - $34.00

  • SkinCeuticals Sheer Physical UV Defense SPF 50 - $34.00

  • Gltytone Hydra Lipid UV SPF 40 - $36.00