Sun Protective Clothing - UPF Rating

UPF Rating

A relatively new rating designation for sun protective textiles and clothing is UPF (Ultraviolet Protection Factor). Unlike SPF (Sun Protection Factor) that traditionally uses human sunburn testing in a laboratory environment, UPF measures both UV radiation transmittance using a laboratory instrument (spectroradiometer) and an artificial light source and translates these results using a mathematical expression based upon the sunburn action spectrum (erythema action spectrum) integrated over the relevant UV spectrum. Theroretically, both human SPF testing and in vitro laboratory instrument testing measure a product's relative ability to protect against minimal sunburn compared to skin that is not protected.

Developed in 1998 by Committee RA106, the testing standard for sun protective fabrics in the United States is the American Association of Textile Chemists and Colorists (AATCC) Test Method 183. This method is based on the original guidelines established in Australia in 1994. Below is the ASTM Standard for Sun Protective Clothing and Swimwear which is considered the industry standard in rating such sun protective clothing:

UPF Ratings and Protection Categories