UPF: What it is and why it matters

  • Ultraviolet Protection Factor (UPF) indicates how much UV radiation (both UVB and UVA) a fabric allows to reach your skin. For example, a UPF 50 fabric blocks 98 percent of the sun’s rays and allows two percent (1/50th) to penetrate, thus reducing your exposure risk significantly.
  • What you need to know: A fabric must have a UPF of 30 to qualify for The Skin Cancer Foundation’s Seal of Recommendation. A UPF of 30 to 49 offers very good protection, while UPF 50+ rates as excellent.

Have fun in sun.

  • You can enjoy yourself in the sun without compromising your skin health or style by wearing sun experiment clothing and bandanas as part of a complete fun-sun protection strategy.
  • To help your skin you chose sun-safe products, look for Sun experiment by skin project and “HAVE FUN WITH THE SUN”.

What makes clothing sun safe?

  • Yes, your clothing shields you from the sun, but not all fabrics and colors provide equal protection. Luckily, you have plenty of options. When shopping for apparel that can effectively shield you from harmful rays, keep these factors in mind:
  • Color: Dark or bright colors keep UV rays from reaching your skin by absorbing them rather than allowing them to penetrate. That’s why these colors offer better protection than lighter shades.
  • Construction: Densely woven cloth, like denim, canvas, wool or synthetic fibers, are more protective than sheer, thin or loosely woven cloth. Check a fabric’s sun safety by holding it up to the light. If you can see through, UV radiation can easily penetrate the fabric and reach your skin.
  • Content: The composition of your fabric really matters. Unbleached cotton contains natural lignins that act as UV absorbers. Shiny polyesters and even lightweight satiny silks can be highly protective because they reflect radiation. High-tech fabrics treated with chemical UV absorbers or dyes prevent some penetration from UV rays.
  • Fit: Loose-fitting apparel is preferable. Tight clothing can stretch and reduce the level of protection offered, as the fibers pull away from each other and allow more UV light to pass through.
  • UPF: Some clothing makers provide UPF labels, which indicate exactly how much of the sun’s rays the garment can shield. Look for our Seal of Recommendation whenever you shop.
  • Coverage: The more skin your outfit covers, the better your protection. Whenever possible, choose long-sleeved shirts and long pants or skirts.
  • Activity: Regardless of UPF, if your clothing gets stretched or wet, it will lose some of its protective ability and become more transparent, exposing your skin to more UV light.

Sun experiment ‘Fiber to Fabric’

Not all Upf clothing is created equal.

  • Innovation in fashion is the first priority of skin project philosophy. We’re unceasingly intense about developing fabrics that matter in contemporary styles made for movement, style and fun.
  • We've developed industry-leading fabrics with performance features like lightweight, soft, breathable, thin, moisture-wicking, fast drying, cooling, water repellant, anti-microbial – all designed for movement, styling and fun.

What makes a fabric sun protective?

  • Factors that affect the level of sun protection provided by a fabric, in approximate order of importance, include weave, color, weight, stretch, and wetness. Getting a fabric wet reduces the protection as much as half, except for silk and Bamberg satin which can get more protective when wet. In addition, UV absorbers may be added at various points in the manufacturing process to enhance protection levels
  • Best way of making our worlds thinnest sun protection fabric and infused with Vitamin ‘E’ in fiber or fabric level.
  • Studies at the  University of Alberta also indicate that darker-colored fabrics offer more protection than lighter-colored fabrics.
  • Even with multiple washings and exposure to sweat, chlorine and salt – our sun protection never washes out.

UPF Rating

Protection Category

% UV radiation Blocked

UPF 15 – 24


93.3 – 95.9

UPF 25 – 39

Very Good

96.0 – 97.4

UPF 40 – 50+


97.5 – 98+

Why we say no to SPF! And yes to UPF.

  • If you see clothing brands labeled as SPF protection, it’s not accurate for fabrics. SPF stands for Sun Protection Factor which measures the amount of time it takes for sun-exposed skin protected with sunscreen or lotion type products to redden from UVB (“burning”) rays. UPF is a broad-spectrum UVA and UVB measure for fabric, and it rates the amount of UV radiation that penetrates a fabric and reaches the skin. A garment with a UPF of 50 only allows 1/50th of the UV radiation falling on the surface of the garment to pass through it. It blocks 49/50ths or 98% of the UV radiation. Clothing brands that cite SPF are not full spectrum protection.
  • SPF stand for sun protection factorand is a measure of how long a sunscreenwill protect you from UVB rays. What does that exactly mean? Well in theory it works like this – let’s say with no sunscreen your skin starts to get red in 20 minutes. An SPF 15 theoretically would allow you to stay in the sun 15 times longer without getting burned, for 5 hours while an SPF 30 theoretically would be double at 30 times and for 10 hours.
  • BUT and that’s a big BUT, it doesn’t account for your skin type, the amount of sunscreenapplied and the intensity and wavelength distribution of UVB rays during the day and by location. 
  • Now that you’ve got SPF down what does UPF mean? UPF stands for Ultraviolet Protection Factor and indicates what fraction of the sun’s UV rays can penetrate fabric. Thus a piece of clothing with a UPF 50 allows around 1/50th of the sun’s UV radiation to reach the skin.
  • UPF, unlike SPF, measures both UVA and UVB penetration.
  • The Bottom Line
  • To make it easier, here’s a little summary:


  • Only measures UVB protection (make sure the sunscreen is labeled ”broad spectrum“ to also get UVA protection)
  • Is the percentage of UVB rays filtered out
  • Applies to sunscreen


  • Measures UVB and UVA protection
  • Is the fraction of the sun’s UV rays that reach the skin
  • Applies to clothing

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