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SPF vs UPF: What's the Difference?

27th January 2022

Most people have at least heard the term ‘sun protection factor’ and have a basic understanding of what it means. In truth, there are two very different ‘factors’ when it comes to sun protection – Ultraviolet Protection (UPF) and Sun Protection (SPF).

These two abbreviations can be uttered in the same breath, as they are both used to measure the ability of a particular product to protect the wearer against sun-based radiation. However, there are more differences between them than similarities, and today we’ll talk about the most prominent ones, so let’s start from the top:

Used for different types of products

Sun-protection Factor is a measure that tests the ability of sun sprays, lotions, balms and similar products to protect skin while Ultraviolet Protection Factor represents the efficiency of fabrics to prevent sun rays from penetrating the material.

Different types of tests are conducted to determine the rating

Basically, UPF tests are conducted on fabrics by special machines and devices while SPF tests are conducted on human volunteers. It may be argued whether SPF tests could be performed on artificially created meat, but such practices are not condoned by reputable medical institutions.

UPF test

The UPF test is practical and relatively simple, although its formula is complex. A piece of fabric is exposed to a beam of ultraviolet radiation under a special sensor, which measures the exact amount of radiation that has managed to pierce it.

The number stated by UPF describes the product’s ability to reduce exposure to UV radiation in fractions. For example, the UPF rating of 20 indicates that the fabric will reduce the exposure time by 20 times; in other words, only 1/20th of the summed UV radiation can pass through.

SPF test

The main reason why SPF tests are conducted on humans (always volunteers) is that an average metric is required from a large group of different individuals. Fabrics can be manufactured to have the same specifics and characteristics, but all people are different and have different innate medical predispositions.

This test measures the time needed for the skin to turn red. As soon as mild burns emerge, the test is complete, and the measurements are taken.

Exposed unprotected skin typically needs approximately ten minutes before it turns red. Once sunscreen is applied, the amount of time multiplies, which is what the metric test conductors are after. The SPF number indicates the ‘time multiplier’ - given that skin needs ten minutes to burn, an SPF rating of 10 means that you would be safe for up to an hour and 40 minutes (100 minutes) before you would need to reapply the sunscreen.

Covered versus Exposed Skin protection

UPF rating describes the ability of clothes to prevent covered skin from becoming red and irritated; SPF rating describes the ability of sunscreen products to prevent exposed skin.

Some may argue that sunscreen remains effective even when a person is clothed. Most experts agree that the majority of sunscreen-based products lose their potency whenever a layer is ‘peeled’ off, which could be done in a number of ways. Sunscreen will stick to the clothes, sweat could dilute them, and it needs to be reapplied constantly.

Passive versus Active protection

It would be safe to label UPF as a ‘passive’ standard while SPF would bear the label of ‘active sun protection’. Essentially, people don’t need to do anything in particular in order to benefit from the ultraviolet protection provided by clothes (UPF). On another hand, sun-protection creams, lotions, and balms need to be applied (SPF).

Additionally, the magnitude of protection provided by clothes is always the same while the thickness of applied layers of sunscreen largely determines its efficiency.

Aside from the fact that their ‘natures’ are different, it’s important to note that SPF-rated products require active participation of product users while SPF-rated products provide the associated benefits passively. Clothes are meant to be worn in a particular way, but there are certain guidelines to be followed to use sunscreen effectively.

Rating Accuracy

Although numerous tests are required to get a fairly precise indicator of any sun-protection product’s efficiency, the accuracy of SPF and UPF ratings is not the same.

First and foremost, the UPF rating describes the percentage of blocked sunrays. Only the weakest and strongest of UPF-rated products offer consistent results while the efficiency of products in between is relative to the intensity of solar irradiance (the strength of sun rays).

For instance, the UPF rating of 15 means that 1/15th of UV rays can pass through. On extremely sunny days, this could be more than enough to get severe sunburns, despite the fact that only a small portion of rays pierced the fabric.

On another hand, the SPF rating is only accurate if the sunscreen is applied properly. Using the right products in the wrong way is as common as using the wrong products ‘effectively’. Not applying enough layers and not reapplying the sunscreen on time usually make people believe that the sunscreens they are using are not as effective as advertised.

Breadth of protection

The main and arguably most important difference between SPF and UPF is the amount of protection they offer from sun-based radiation; better said, it’s their ability to protect against UVA, UVB, or both types of ultraviolet radiation.

UVA rays are sun rays with the longest wavelength and are wrongly considered by many as ‘harmless’. Although they are weaker than UVB rays, UVA rays are the ones causing skin redness, as we are constantly exposed to them.

UVB rays are partially absorbed by our planet’s ozone layer, but some manage to get through. They are more intense and prone to causing severe burns.

UPF-rated products are tested for both UVA and UVB rays and are generally designed to protect against both in equal measure. Sunscreen products (SPF) are meant to protect against UVB rays exclusively, which is the main reason why so many people get mild burns even after using the products properly.

Sunscreens, lotions, balms, and similar SPF-rated products that feature ‘Broad Spectrum’ labels are manufactured to protect against both UVA and UVB rays, just like UPF-rated products.

We hope that this brief guide was useful to you and that you have learned something new about  the differences between SPF and UPF. Make sure you are staying safe in these times we are all going through and have a good one, guys!

Please note the contents of this post is information only and general in nature.
If you require advice it is best to contact one of our shade specialists who can review your particular circumstances and then provide tailored advice according to your needs.