How UPF Rating System Works
UPF rating system need to be explained, so when coming to choose a UPF rating clothing, you understand what you are shopping for. These UPF ratings are a represent the protective level, expected from the fabric.
The way these level is reached is by laboratory tests, each manufacturer does for their own clothes. There are three international standards for UPF clothes, by the Australian, the European and the US. They all measure the protection level and rate it from 1-50.
UPF Rating Explained
At the labs scientists measure the amount of UV rays which manage to pass through the fabric. This is done in optimal environment. Which means no stretching, and on dry clothing (unless its sun guard swimsuits). On one side UV light is produced, and on the other side of the fabrics, the amount of UV light is recorded.
The UPF ratings are the percentage of protection each fabric has compared to a non UPF fabric. So UPF 30 means that 30 units of UV rays are blocked, while 1 unit will pass through. So 29 units are blocked by the fabric, and 1 unit will reach the skin. 29 out of 30 means 96.7% of protection.
UPF 50+ Rating Explained
As shown in the example above, UPF 50 means out of 50 UV unites only 1 will penetrate the clothing. This means 49 units of ultraviolet rays are reflect, absorbed or blocked. This means less than 2% of UV passing through the fabric. This is a 98% rate.
Any fabric which can block more than 98% of the UV rays will get the 50+ rating, as there is no higher way to rate the UPF protectiveness level.
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