UPF 50+ is a sun-protection rating used for clothing and other textiles. UPF stands for Ultraviolet Protection Factor. A fabric rated UPF 50 allows approximately 1/50th of the relevant ultraviolet radiation to pass through it, corresponding to about 2% transmission and approximately 98% being blocked by the rated material.
The rating is particularly relevant for clothing worn during long periods outdoors, including surfing, kitesurfing, swimming and other activities around the coast. However, UPF describes the protection provided by the rated material and covered area, not complete protection for your entire body.
Understanding the UPF Rating
Ultraviolet Protection Factor describes how effectively a textile reduces ultraviolet radiation reaching the skin beneath it. The basic principle is straightforward: a higher UPF number means a smaller proportion of relevant UV radiation passes through the material.
- UPF 15: approximately 1/15th of the relevant UV radiation is transmitted.
- UPF 30: approximately 1/30th is transmitted.
- UPF 50: approximately 1/50th is transmitted.
Expressed as approximate percentages, UPF 15 corresponds to about 93.3% of relevant UV radiation being blocked, UPF 30 to about 96.7% and UPF 50 to about 98%.
The difference between UPF 30 and UPF 50 can appear relatively small when expressed as a percentage blocked. Looking at transmission makes the distinction clearer. UPF 30 corresponds to approximately 3.3% transmission, while UPF 50 corresponds to approximately 2%.
What Does the + in UPF 50+ Mean?
The plus sign indicates that the material has performed beyond the threshold represented by the highest labelled numerical category under the applicable rating system. The exact classification rules depend on the test standard being used, so UPF 50+ should not be interpreted as one universal numerical value above 50 across every standard.
What remains consistent is that UPF 50 and UPF 50+ represent very high levels of textile UV protection. Under the Australian sun-protective clothing classification, for example, UPF 50 and 50+ are classified as excellent protection.
UPF 50+ does not mean complete UV protection. Some ultraviolet radiation can still be transmitted through the material, and skin not covered by the garment remains exposed.
How Is UPF Measured?
UPF is determined through textile testing that measures ultraviolet transmission across the relevant UV spectrum and uses those measurements to calculate the protective performance of the material.
The rating accounts for ultraviolet wavelengths relevant to skin damage rather than simply measuring how dark or opaque a fabric looks to the human eye. This is why a tested rating provides more useful information than assuming protection from appearance or fibre composition alone.
Different standards and testing systems can use different procedures and classification rules. When evaluating a specific product claim, the applicable test method and the conditions under which the material was tested are therefore relevant.
Does UPF Protect Against UVA and UVB?
UPF testing evaluates textile protection across ultraviolet wavelengths that include both UVA and UVB. This is important because the two forms of ultraviolet radiation affect the skin differently.
UVB is strongly associated with sunburn, while UVA penetrates more deeply into the skin and contributes to long-term skin damage. Both contribute to skin cancer risk.
A high UPF rating therefore provides information about the overall UV protection of the tested textile rather than describing protection against only one narrow part of the ultraviolet spectrum.
Why Different Fabrics Provide Different UPF Protection
The fibre itself is only one part of textile UV protection. The structure, colour, stretch and condition of the finished fabric can also influence how much ultraviolet radiation passes through it.
Factors that can influence UV transmission include:
- Fabric density: tightly constructed fabrics generally leave less space for UV radiation to pass through.
- Weave or knit structure: more open structures can allow more radiation through than dense constructions.
- Colour: dyes and pigments can influence how much UV radiation a fabric absorbs.
- Stretch: stretching some fabrics can open the structure and reduce protection.
- Wetness: water can change the protective performance of some textiles.
- Wear and condition: ageing, thinning or damage can alter how a fabric performs over time.
- Special treatments: some textiles use treatments or additives designed to increase UV protection.
This is why fibre composition alone cannot reliably tell you the UPF of a finished garment. A polyester or nylon shirt is not automatically UPF 50+ simply because of the material listed on its label.
For a deeper explanation of these factors, see our guide to how UPF clothing works.
Stretch, Water and Real-World Use
A textile does not remain in a perfectly static condition once it becomes clothing. It stretches, gets wet, moves across the body and gradually changes through use and washing.
Stretch is particularly relevant for close-fitting waterwear. As some elastic fabrics stretch, the textile structure can become more open, potentially allowing more ultraviolet radiation to pass through.
Wetness can also change the UV protection of some fabrics, although the effect is not identical for every textile. Material, colour, construction and the way the product has been tested all matter.
For clothing designed specifically for use in and around water, an appropriate tested UPF claim is therefore more useful than assuming a fabric will provide adequate protection simply because it appears thick or opaque when dry.
UPF 50+ vs SPF 50
UPF and SPF are both associated with sun protection, but they are different rating systems and should not be treated as interchangeable numbers.
UPF is used for textiles and describes the ultraviolet protection provided by material. SPF, or Sun Protection Factor, is used for sunscreen and is determined through a different testing system.
UPF 50 and SPF 50 therefore do not mean exactly the same thing simply because both use the number 50.
For a deeper comparison, see SPF vs UPF.
Coverage Matters as Much as the Rating
A UPF rating only protects the skin covered by the rated material. A long-sleeve garment can provide rated coverage across the torso and arms, for example, while the face, hands and other uncovered areas remain exposed.
This is why a high UPF rating should not be interpreted as complete sun protection. Garment design and coverage determine how much of the body actually benefits from the rated material.
Broad-spectrum sunscreen can complement clothing on exposed skin, while shade, appropriate headwear and sunglasses can provide additional forms of protection.
What Does UPF 50+ Mean Around Water?
UPF-rated clothing can be particularly relevant around the coast because surfing, kitesurfing, swimming and other watersports can involve extended periods outdoors with limited access to shade.
This becomes easy to understand in sunny watersports environments. At Prasonisi on Rhodes, extended sessions on and around the water can make clothing coverage an important part of managing sun exposure. The same principle applies in destinations such as Safaga, where watersports can involve substantial time outdoors and on the water.
These destinations are examples rather than fixed sun-protection recommendations. UV intensity changes with location, season, time of day, cloud cover and atmospheric conditions, so current local conditions and the UV Index should always be considered.
Water and surrounding surfaces can contribute to reflected UV exposure, while water and wind can make hot or sunny conditions feel less intense. This can make it easier to underestimate total exposure during a long session.
For watersports, the practical value of a UPF garment therefore comes from more than the rating alone. Coverage, fit, comfort, freedom of movement and how the textile performs in the conditions for which it was designed all matter.
This is part of the wider reason people can underestimate UV exposure around water.
Does Everyday Clothing Have a UPF Rating?
Most clothing blocks some ultraviolet radiation, but the level of protection can vary considerably. A garment does not need a UPF label to reduce UV transmission, but without testing it can be difficult to know how much protection the fabric actually provides.
Dense fabric structures generally provide greater protection than open or loosely constructed materials. Stretch, moisture, colour and wear can further influence performance.
A tested UPF rating provides a clearer reference because the textile has been specifically evaluated for ultraviolet protection.
What Does UPF 50+ Mean for Waterwear?
For technical waterwear, UPF 50+ indicates a high level of textile UV protection while the garment is covering the skin. It does not tell you everything about how suitable the garment is for a particular watersport.
Fit, stretch, freedom of movement, drying characteristics, coverage and the conditions in which the garment will be used remain important. A close-fitting rashguard and a regular-fit water shirt can therefore both use UPF 50+ fabric while providing different experiences in the water.
The Water Peak's Performance-Fit Coastech™ Rashguard combines UPF 50+ protection with a close second-skin performance fit, while the Regular-Fit Visibility Water Shirt combines UPF 50+ protection with a more relaxed performance fit.
Putting UPF 50+ in Perspective
UPF 50+ represents a very high level of textile UV protection. UPF 50 corresponds to approximately 2% of the relevant ultraviolet radiation being transmitted through the rated material, or approximately 98% being blocked.
The rating is important, but it is only part of the picture. Coverage, fabric construction, stretch, wetness, garment condition and the amount of skin left exposed all matter in real-world use.
For long periods around the coast or on the water, UPF-rated clothing can form a practical part of a broader sun-protection strategy, particularly when combined with appropriate protection for the areas of skin that remain exposed.