Font Size
A
A
A

Definition of Sun protection factor (SPF)

Sun protection factor (SPF): A number on a scale for rating the degree of protection provided by sunscreens. SPF stands for Sun Protection Factor.

SPF numbers on a package can range from as low as 2 to as high as 100. These numbers refer to the product's ability to screen or block out the sun's burning rays. It is a common mistake to assume that the duration of effectiveness of a sunscreen can be calculated simply by multiplying the SPF by the length of time it takes for him or her to suffer a burn without sunscreen, because the amount of sun exposure a person receives is dependent upon more than just the length of time spent in the sun. The amount of sun exposure depends upon a number of factors including the length of exposure, time of day, geographic location, and weather conditions.

Source: MedTerms™ Medical Dictionary
http://www.medterms.com/script/main/art.asp?articlekey=5590
Last Editorial Review: 6/14/2012

Medical Dictionary Definitions A - Z

Search Medical Dictionary