What's the difference between SPF and UPF?

You might have asked yourself...what (or even if) there's a difference between UPF & SPF?

Yes there is...hold onto your hats!

Ultraviolet Protection Factor (UPF) and Sun Protection Factor (SPF) are both measures that protect us from the sun.
  • UPF is how much protection a fabric gives us and used to measure a garment’s protection
  •  SPF is the measure of how long it will take before your skin burns and used to measure a sunscreen’s protection
  • Both are extremely important to prevent skin damage, aging, and reduce your risk of skin cancer. 

What is UPF?

Ultraviolet Protection Factor  (UPF) tells us how much UV radiation a fabric blocks or absorbs.

Clothing can block harmful sun rays and is a good way to protect yourself from the sun. However UPF tested fabrics offer more protection - UPF will tell you how much sun can get through. 

UPF measures both ultraviolet A (UVA) and ultraviolet B (UVB) rays.

UVA rays can cause the skin to age (and for you science / tech babes UVA rays are longer in wavelength) .

UVB rays have a short wavelength and cause the skin to burn. 

Both UVA and UVB rays are harmful to the skin because they can damage the cell structure and DNA, which could lead to premature aging and can lead to skin cancer. 

So then what is SPF?

Sun protection factor (SPF) is a measure that indicates how long it takes for your skin to turn red (i.e. burn) if you are wearing that level of SPF.

For example, an SPF 20 indicates that it will take your skin 20 times longer to burn than if you didn’t have sunscreen. If your skin turns red after 10 minutes in the sun, then theoretically, an SPF 20 will allow you to be in the sun for about 3 hours and 20 minutes.

Theoretically The higher the SPF, the better or longer the protection, but it's more complicated.

The Environmental Working Group (EWG) points out that super-high SPFs don't actually block out that many more skin-damaging rays.

SPF 50 blocks 98 percent of UVB rays, while SPF 100 blocks 99 percent.

It’s important to note that SPF only measures UVB, so look for a sunscreen that specifically offers both UVA and UVB protection. Also, because it’s a cream, it needs to be applied thick enough and re-applied when directed.

If you are swimming or in the water, it’s important to use a water-resistant sunscreen. 

Here's the thing...many of us forget to apply (and re-apply) sunscreen daily (including when it's overcast or winter) - and further our tinted SPF moisturizer isn't enough.

Wearing UPF rated clothing and hats allows you to go about your day without thinking about applying or reapplying. That's not to say you shouldn't wear sunscreen. When you wear UPF you’re protecting your skin from harmful rays for as long as you're wearing your clothing.

UPF Rating Scale

UPF measures the percentage of UV rays that are blocked in a fabric.

  • The higher the UPF, the more protection that fabric will offer.
  • A UPF factor of  50, blocks 98% of the sun’s rays.
  • This means that 50 UV units, it blocks 49, and only 1/50 pass through it.
  • According to The Skin Cancer Foundation, a fabric must have a UPF of 30 (blocks 96.7% of rays) and up to qualify for their seal of recommendation.

If you're wondering how to choose and determine if something is sun safe, check out our list here.