Ultraviolet Protection Factor

What does UPF mean?

When we use the term UPF on the website, it is an abbreviation of "Ultraviolet Protection Factor". UPF indicates how much UV radiation (both UVB and UVA) a fabric allows to reach the skin. For example, a fabric with UPF 50 blocks 98% of the sun’s rays and allows only 2% (1/50) to pass through, significantly reducing your exposure.

Children who have finer and more sensitive skin than adults, should not stay in the sun without being covered or otherwise protected from the harmful UV-rays. Summer hats are a great form of protection from the sun, and at MP Denmark our summer hats are labeled with UPF50. The summer hats have either received a special treatment or impregnation on the surface of the fabric or are produced by a fabric with a weave that makes the hat possess UPF50. The fabric used to produce our summer hats have therefore been sent for testing for UV radiation, where they have achieved UPF50 protection. 

What does the number mean?

UPF usually has a number after it, for example on this site, where we use UPF50, and this means that every time 50 rays from the sun hit the fabric of our summer hats, there is 1 ray that penetrates. Likewise, if a product has UPF20, 1 ray penetrates for every 20 rays. The higher the number, the greater the protection.

UPF50 protects against 98% of the sun's rays – and here is how you calculate it:
At 50 rays, 1 ray penetrates, which means that at 100 rays, 2 rays penetrate. Thus, 2% of the sun's rays penetrate, which means that the remaining 98% is blocked.

What is the difference between SPF and UPF?

Most people are probably familiar with the term SPF, which is an abbreviation of "Sun Protection Factor". It is this designation that we see on sunscreen. SPF is a standard used to measure the effectiveness of sunscreen. Here it is calculated in a different way. It is said that SPF30, for example, extends the time it takes for you to get sunburned by 30 times. SPF15 extends the time by 15 times, etc. It is therefore an expression of how much longer you can stay in the sun without getting sunburned compared to if you did not wear sunscreen.

SPF is also said to only protect against UVB (unless anything else is written on the product), whereas UPF protects against both the sun's UVA and UVB rays.

If you bathe/sweat, the SPF/sunscreen will be washed off your skin, and protection therefore depends on applying new layers to get the full effect. The UPF in MP Denmark's hats is not easily washed off, and not at all if it concerns the fabric's weave. You can therefore count on the protection even after a lot of use, and washes.

Read more about UPF here.