On a dress, a swimsuit, or a summer shirt, a few discreet letters sometimes appear: UPF 50+.
These are not technical details, but a promise.
The promise of tamed light, respected skin, and clothing that protects as much as it beautifies.
However, few people truly know what this acronym means.
Here is the complete guide to understanding what a sun protection label hides — and why it changes everything.
What is UPF?
UPF stands for Ultraviolet Protection Factor.
It is the index that measures a fabric's ability to block ultraviolet rays, those invisible rays responsible for tanning, skin aging, and sunburn.
In other words, UPF indicates the proportion of UV rays that do not reach the skin.
The scale is simple:
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UPF 5 → 1 in 5 rays pass through the fabric (80% blocked)
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UPF 25 → 1 in 25 pass (96% blocked)
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UPF 50+ → less than 1 in 50 pass (98% blocked or more)
The “+” symbol means that the protection exceeds the required threshold for the maximum rating.
Thus, a UPF 50+ fabric can block up to 99% of UVA and UVB according to the European standard EN 13758-1.
Where does this certification come from?
The UPF mention is not improvised: it is awarded after laboratory tests.
The standard EN 13758-1, recognized in Europe, precisely defines the method.
The fabric is exposed to a lamp reproducing the solar spectrum, then measured before and after contact with:
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seawater,
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chlorine,
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artificial perspiration,
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and several wash cycles.
Each sample is then evaluated according to its UVA and UVB filtering capacity, its surface condition, and its stability over time.
If the performance is maintained, the garment can display the corresponding protection level.
🔍 Note: serious manufacturers indicate not only the UPF, but also the standard used (EN 13758-1 in Europe, AS/NZS 4399 in Australia, AATCC 183 in the United States).
This is the only way to guarantee true compliance.
UPF and SPF: do not confuse
The SPF (Sun Protection Factor) concerns sunscreen creams and indicates the time for which the skin can be exposed before burning.
The UPF, on the other hand, concerns clothing and measures the amount of radiation blocked.
One is applied, the other is worn.
But their logic is the same: to filter the sun before it reaches the skin.
According to the Skin Cancer Foundation, a fabric rated UPF 50+ offers superior protection to SPF 50 cream, as it does not degrade with wind, sweat, or time.
What influences the level of protection
Not all fabrics react to light in the same way.
Four main criteria determine their UPF factor:
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Fabric density: the tighter the fibers, the less light passes through.
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Color: dark shades absorb more UV, but also retain heat.
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Material: polyester and polyamide naturally offer superior protection to cotton or linen.
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Humidity: a wet fabric loses up to 50% of its filtering capacity.
This is why UPF 50+ certified clothing must be tested under real conditions (salt, sweat, water).
This label is therefore not a marketing argument, but a proof of resistance and durability.
Why choose UPF 50+?
Because it is the highest level of protection recognized by the European standard.
UPF 50+ certified clothing blocks 98% of UV — a threshold which, according to the CNRS, almost completely reduces the risk of burns and cellular alteration during prolonged exposure.
But beyond the number, it is mental comfort:
the comfort of no longer having to fear the light, of being able to walk, read, swim, without calculating.
Clothing becomes an invisible filter, a form of freedom.
How to read a sun label
On a textile label, several mentions may appear:
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UPF XX (according to EN 13758-1): indicates the standard and the actual level.
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UV Standard 801: a stricter complementary certification, testing wet and aged fabric.
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UVA/UVB Protection: specifies the type of rays blocked.
An "anti-UV" garment without a standard mention offers no real guarantee.
At Jayne, each fabric is tested by an independent laboratory and accompanied by a certificate of conformity — because trust, too, is woven in transparency.
At Jayne
At Jayne, we consider the UPF 50+ standard as a foundation, not an end.
Our fabrics — whether Italian, Japanese, or French — are chosen for their texture, fluidity, and breathability.
Each creation combines durable sun protection and timeless aesthetics: technical voile shirts, openwork dresses, swimsuits with clean lines.
Wearing Jayne means reconnecting with the light, without ever enduring it.
Sources
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World Health Organization (WHO) – Solar Ultraviolet Radiation: Global Burden of Disease, 2021
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CNRS, Studies on UV transmission according to textile density, 2019
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Skin Cancer Foundation, Understanding UPF Clothing and UV Exposure, 2022
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European Standard EN 13758-1:2001, Textiles – Protection against ultraviolet radiation – Test method and marking requirements
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UV Standard 801, Testing Method for UV Protective Textiles, 2020
