Sunscreen (SPF)

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

• Understanding Serums
• How to Choose a Cleanser
• Tinted Sunscreen
• SPF Powder
• Mineral Sunscreen
• Lip Treatment (SPF)
• Chemical Sunscreen
• Why Does My Sunscreen Leave a White Cast?

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