UPF FAQ

The 10 Most Common Questions About Sun Protection Clothing—Answered Clearly

If you’ve ever looked into sun protection clothing, you’ve likely come across a mix of claims, technical terms, and conflicting advice. It can feel unclear what actually matters—and what’s just marketing.

This guide breaks down the 10 most frequently asked questions about UPF clothing, with clear explanations grounded in how these garments are actually tested and how they perform in real life.

What is UPF clothing?

UPF stands for Ultraviolet Protection Factor. It measures how much ultraviolet (UV) radiation can pass through a fabric and reach your skin.

For example, a garment rated UPF 50 allows only about 1/50th of UV radiation to pass through—meaning it blocks approximately 98%.

Unlike regular clothing, UPF-rated garments are tested in controlled laboratory conditions using standardized methods. These tests measure how much UV light passes through fabric across both UVA and UVB wavelengths, which are the types of radiation responsible for skin aging and sunburn.

Organizations like the Skin Cancer Foundation and the Environmental Protection Agency recognize UPF clothing as a reliable form of sun protection.

How is UPF different from SPF?

UPF and SPF are often confused, but they measure different things.

SPF (Sun Protection Factor) is used for sunscreen and primarily measures protection against UVB rays, which cause sunburn. UPF, on the other hand, measures how fabric blocks both UVA and UVB rays.

There’s also a practical difference. Sunscreen must be applied correctly and reapplied regularly to remain effective. Clothing, once worn, provides consistent coverage without needing to be reapplied.

For this reason, the American Academy of Dermatology recommends using both clothing and sunscreen together for complete protection.

Does regular clothing protect you from the sun?

Yes—but not always very well.

All clothing provides some level of protection, but the amount varies significantly depending on the fabric. A lightweight cotton T-shirt, for example, may only block a small percentage of UV radiation, especially if it is light-colored or loosely woven.

The Centers for Disease Control and Prevention notes that tightly woven fabrics offer better protection, while thin or sheer materials allow more UV to pass through.

This is why two shirts can look similar but perform very differently in the sun.

What fabrics provide the best sun protection?

The effectiveness of a fabric comes down to how tightly it is constructed and what it is made from.

Fabrics that tend to perform best include:

Tightly woven materials that leave little space for light to pass through
Synthetic fibers like polyester and nylon, which naturally absorb more UV radiation
Heavier fabrics with more structure and density

The Environmental Protection Agency emphasizes that fabric density is one of the most important factors in UV protection.

That said, advances in textile design mean that some lightweight fabrics can still achieve high UPF ratings through construction and finishing techniques.

Does color make a difference?

Yes, but it’s not the only factor.

Darker or more saturated colors tend to absorb more UV radiation, which reduces the amount that reaches your skin. Lighter colors, especially white, can allow more UV to pass through if the fabric itself is not tightly woven.

However, fabric structure usually matters more than color alone. A well-constructed light fabric can outperform a loosely woven dark one.

Does UPF clothing lose its effectiveness over time?

It can, depending on how the protection is achieved.

If a garment’s protection comes primarily from its tight weave, it will generally maintain its performance over time. However, if the fabric relies on added treatments to enhance UV protection, those treatments may gradually diminish with repeated washing and wear.

Over time, all fabrics experience some level of breakdown—fibers can stretch, thin, or shift—which may affect how much UV they block.

The Skin Cancer Foundation notes that wear, laundering, and overall garment care can influence long-term effectiveness.

Does stretching or getting clothing wet affect protection?

Yes, both can make a noticeable difference.

When fabric stretches, the spaces between fibers increase, allowing more UV radiation to pass through. Similarly, when fabric becomes wet, its structure changes in a way that can reduce its ability to block UV light.

Because of this, a garment may perform differently at the beach or during active use compared to how it was tested in the lab.

The Centers for Disease Control and Prevention highlights the importance of considering real-world conditions when relying on clothing for sun protection.

Is UPF clothing better than sunscreen?

It’s not a matter of one replacing the other—they work best together.

Clothing provides consistent protection without needing to be reapplied, making it especially effective for larger areas of the body. Sunscreen, on the other hand, is essential for exposed areas like the face, hands, and neck.

Public health guidance from the Environmental Protection Agency recommends combining multiple strategies: clothing, sunscreen, and shade.

How can you tell if clothing is truly UPF-rated?

The most reliable indicator is clear labeling and transparency.

Look for:

A stated UPF rating (such as UPF 30 or UPF 50+)
Reference to standardized testing methods
Consistency across the brand’s products

Without formal testing, any claim about UV protection is an estimate rather than a verified measurement.

Who should wear sun protection clothing?

Sun protection clothing is not just for beach days or outdoor sports—it’s relevant for everyday life.

Anyone who spends time outdoors can benefit, especially those concerned with:

Long-term skin health
Premature aging
Cumulative sun exposure

The American Academy of Dermatology encourages incorporating sun protection into daily routines, not just occasional activities.

A more practical way to think about it

At its core, sun protection clothing works because it removes guesswork. It doesn’t rely on timing, reapplication, or perfect conditions. It simply creates a consistent barrier between your skin and UV radiation.

The real question isn’t just how well a garment performs in a lab—it’s whether it’s something you’ll actually wear regularly. Because consistency is what ultimately determines how effective any form of sun protection will be.

Where Some Sun fits in

At Some Sun, the focus is on combining verified protection with everyday wearability. Fabrics are independently tested to recognized standards, but just as importantly, they’re designed to feel and look like pieces you already want to wear.

The goal is simple: make sun protection something that fits into your life naturally—so it becomes a habit, not an extra step.