How is SPF calculated?
Sun Protection Factor (SPF) is calculated by measuring how long a sunscreen protects the skin from UV rays compared to how long it would take for unprotected skin to burn. For example, if a sunscreen with SPF 30 allows a person to stay in the sun for 30 times longer without burning than if they were not wearing any sunscreen, it is said to have an SPF of 30. This means that SPF indicates the level of protection against sunburn, but not necessarily against other types of skin damage.
Key points:
- SPF measures the time a sunscreen protects against sunburn.
- Higher SPF numbers indicate more protection from UV rays.
- SPF is determined through controlled laboratory testing.
- Factors like skin type and application amount affect effectiveness.
This text has been fact-checked for accuracy by medino's clinical team.