UPF Protection Ratings for Clothing

UPF stands for Ultraviolet Protection Factor. It is a rating used for fabrics and clothing to describe how much ultraviolet radiation passes through the material.

SPF and UPF are related ideas, but they are used for different things:

• SPF is used for sunscreen.
• UPF is used for textiles and clothing.

What does a UPF number mean?

A UPF 30 fabric allows approximately 1/30 of the relevant UV radiation to pass through it, which means it blocks about 96.7% under the conditions of the test.

A UPF 50 fabric allows approximately 1/50 through, blocking about 98%.

UPF 50+ is generally used for fabrics providing excellent UV protection at or above the upper end of the rating scale used by the relevant standard.

UPF ratings take both UVA and UVB transmission into account, unlike sunscreen SPF, which is primarily based on sunburn protection.

Common UPF ratings

• UPF 15: around 93% of UV blocked.
• UPF 30: around 96.7% blocked.
• UPF 50: around 98% blocked.
• UPF 50+: excellent protection under recognised rating systems.

Different countries and standards may use slightly different classification labels, so the garment label should always be read in context.

How is UPF tested?

In the United States, several established textile standards are used together when testing and labelling UV-protective fabrics.

AATCC TM183 measures the amount of ultraviolet radiation transmitted through or blocked by a fabric using laboratory instrumentation. The method can evaluate specimens in dry or wet conditions.

ASTM D6544 covers preparation of textiles before UV-transmission testing. It uses standardised exposures such as laundering, simulated sunlight and chlorinated pool water to represent ageing and seasonal use.

ASTM D6603 provides guidance for labelling UV-protective textiles using UPF values obtained through recognised testing.

Does a UPF label tell you everything?

No. The fabric rating is important, but the garment design also determines how much skin is actually covered.

A UPF 50 sleeveless top provides excellent protection to the fabric-covered area, but it does nothing for exposed shoulders and arms. Long sleeves, collars, longer hems and wider coverage can increase the total area physically protected.

Can ordinary clothing provide UV protection?

Yes. Clothing does not need a UPF label to block UV radiation. Dense fabrics, darker or brighter colours, thicker materials and loose-fitting garments can provide useful protection.

The difference is that a tested UPF garment gives you a measured rating rather than an estimate based on appearance.

Read more about the factors that influence sun-protection fabric.

What can reduce the protection of clothing?

Protection can change with fabric construction and use. Stretching can open spaces between fibres, wear can thin a fabric, and wetness can alter UV transmission in some materials.

That is one reason recognised testing and ageing protocols are useful: they provide more information than simply holding a garment up to the light.

What should you look for when buying UPF clothing?

• A clear UPF rating from a recognised testing system.
• UPF 50 or 50+ when high protection is desired.
• Enough coverage for the activity.
• A comfortable fit that is not stretched tightly across the skin.
• Fabric suitable for swimming, sport or repeated washing if that is how it will be used.

For practical buying considerations, see our sun-protective clothing guide.

UPF ratings apply to the material or garment under specified test conditions. Always follow the care instructions provided by the manufacturer.

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