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You are here: Home > Know Your Skin > Sunscreen & Protection Info > SPF & UPF - Knowing the BIG Difference
SPF & UPF Ratings - Know the BIG Difference!

A question that we have received over the years is “What is the difference between UPF and SPF protection factors?” This is very important, because there is a huge difference. Most of us are used to hearing SPF as a rating for sun screen you apply to the skin, and that is exactly what it is meant for. Since sun protective clothing has started to take rise, we are hearing more about UPF Ratings. SPF and UPF exist because they measure two different things. SPF is primarily used for sun screen's that are applied to the skin and is only an indicator of the reddening factor produced by exposure to the sun. UPF ratings measure the amount of UV radiation that the fabric blocks. Since clothing is a completely different application, there are different standards and it means a lot when it comes to sun protection. 

SPF stands for Sun Protection Factor. SPF values indicate a function of skin reddening. It is the ratio of UV radiation dose required to produce recognizable redness on skin that has been protected with a sunscreen from the UV radiation dose required to produce the same redness on unprotected skin (using a clinical test procedure on human skin). SPF tells you how much longer it will take for your skin to begin to redden with the product on than if your skin was unprotected. The percentage of burning UV rays that a product blocks does not increase proportionally with the SPF value. – Source Int’l UV Testing Labs

UPF stands for Ultraviolet Protection Factor. It is the amount of ultraviolet radiation that a fabric blocks.  It is the ratio of the average effective ultraviolet radiation (UVR) irradiance transmitted and calculated through air to the average effective UVR irradiance transmitted and calculated through fabric. Hence UPF values are used in the Fabric's UV transmittance test by spectrophotometer equipment. – Source Int’l UV Testing Labs

Sun-protective clothing is any garment that can provide adequate protection from the sun. Generally speaking, clothing must have a UPF value of 15 to 50+ (blocks 93 - 98% of UV radiation), and cover or shade sufficient skin to protect a person from the damaging rays of the sun. – Source Int’l UV Testing Labs

In conclusion, it’s very easy to understand why you shouldn’t purchase clothes without a UPF Rating. The Sun Protective Factory felt so strongly about this, in the 1990s, when the FDA discontinued regulating sun protective clothing, the Solar Protective Factory took the lead in developing performance durability testing standards by working with the American Society for Testing and Materials (ATSM). The CEO of SPF served as the chairman of the ASTM committee, working with the Federal Trade Commission (FTC) and the Consumer Product Safety Commission (CPSC) to establish UPF protocols and label standards with are presently used in the United States. SPF ratings, in our opinion, were meant to rate sun screens you apply to the skin, they give absolutely no information about the rating of the fabric, therefore it's not a factor that will benefit you in knowing anything about the ability of the fabric to block UV rays. 

Our recommendation for our customers and readers is to NOT purchase any sun protective clothing item that does not include a UPF Rating and you may run across them when shopping for sun protective fabrics, although it is rare. It's also a good idea to look for seals of approval from organizations such as The Melanoma International Foundation and The Skin Cancer Foundation.

It's easy to remember!

UPF is for fabrics

SPF is for skin applications



All source information is from the International UV Testing Laboratories

Aurora, CO 80016
United States
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