Product Types

Sunscreen (SPF)

Written by Reviewed by the SYNC editorial team Published Last reviewed Editorial standards

Sunscreen (SPF) — a topical product that helps protect skin from ultraviolet radiation, with SPF (Sun Protection Factor) indicating how well it guards against UVB rays that cause sunburn. Broad-spectrum formulas also help defend against UVA rays, which contribute to skin aging and long-term damage.

Key points

  • SPF measures protection against UVB rays, while 'broad spectrum' indicates coverage against both UVA and UVB.
  • Dermatology guidance commonly recommends a broad-spectrum sunscreen of at least SPF 30 for daily use.
  • Sunscreen should be applied generously and reapplied roughly every two hours, and more often after swimming or sweating.
  • No sunscreen blocks all UV rays, so pairing it with shade, clothing, and hats offers fuller protection.

Frequently asked

What does SPF actually mean?

SPF stands for Sun Protection Factor and reflects how well a product protects against UVB rays that cause sunburn. A higher number offers more UVB protection but is not a measure of how long you can stay in the sun.

How much sunscreen should I apply?

Most adults need about a shot-glass amount for the body and roughly a quarter teaspoon for the face and neck to reach the labeled SPF. Applying too little significantly reduces the protection you get.

Related topics

This is a foundational entry in the SYNC Skin Encyclopedia and is expanded over time. Educational information only — not medical advice.

Encyclopedia

Further reading

This entry was written and checked against the sources below. They are published by clinical and scientific bodies, they are listed most readable first, and each one opens in a new tab. They are background for the whole entry rather than footnotes to individual sentences.

  1. How to select a sunscreen American Academy of Dermatology Clinical guidance aad.org
  2. Sunscreen FAQs American Academy of Dermatology Clinical guidance aad.org
  3. How to decode a sunscreen label American Academy of Dermatology Clinical guidance aad.org
  4. Sunscreens and Photoprotection StatPearls (NCBI Bookshelf) Reference text ncbi.nlm.nih.gov
  5. Ultraviolet radiation and human health DermNet NZ Clinical guidance dermnetnz.org
  6. Ultraviolet (UV) Radiation U.S. FDA Regulatory and safety fda.gov

SYNC does not publish medical advice. Nothing here replaces a consultation with a doctor or a pharmacist about your own skin.