What Is SPF and What Does It Stand For?

Is there anything that screams “summertime” quite like the smell of sunscreen? It immediately transports you back to your childhood—carefree days spent at summer camp, splashing around in the pool, and hanging out with friends.

Through all your years, sunscreen has been there for you, to protect your skin, keep you safe from UV radiation, and prevent signs of aging. But despite our familiarity with sunscreen, one thing still remains a mystery for many: what in the world is SPF?

If you’re like most people, you’ve lived your life by one rule: the more SPF, the better. But is that really true? What does SPF even mean? How does it work? Today, we’re going to answer those questions for you—and so much more. Let’s demystify SPF.

  • What Is Sunscreen?
  • What Is SPF?
  • What Do the SPF Levels Mean?
  • Which SPF is Best for Your Face?
  • What Factors Can Impact the Level of SPF You Need?
  • How Do You Find a Sunscreen with the Right Level of SPF?
  • What Is Broad-Spectrum Sunscreen?
  • How Should I Apply Sunscreen?


What is Sunscreen?

Before we can dive into the particulars of SPF, the first step is understanding the basics of sunscreen. The sun omits two types of UV rays that are particularly harmful to your skin: UVA and UVB rays. UVA rays penetrate deep into the skin, causing long-term damage like aging and wrinkles. UVB rays, on the other hand, are shorter than UVA rays.

They burn the surface of your skin, causing immediate damage like sunburns and skin cancer in the long run. Sunscreen is designed to protect your skin from the sun’s damaging rays. It does so in a variety of ways, including absorbing and deactivating, degrading, and reflecting the rays.

What is SPF?

Despite the fact that very few people know what it is, SPF is actually pretty straightforward. SPF stands for “Sun Protection Factor”, and is a measure of the sunscreen’s ability to protect your skin from UVB rays. The basic calculation works like this: “If it takes 1 minute for your unprotected skin to start turning red [in the sun], using an SPF 15 sunscreen theoretically prevents reddening 15 times longer.”

Say you purchase an SPF 30 sunscreen. If it typically takes 10 minutes until your skin starts to burn, by using the SPF 30, you’re theoretically protected from the sun for 300 minutes, or 5 hours.

It’s important to remember that SPF only protects against UVB rays; those are the rays that are causing the “reddening”, or surface burns. SPF doesn’t account for UVA rays; those are the rays that cause long-term damage including aging and wrinkles.

UVA rays can do a lot of damage before your skin turns red. Treat skin redness and prevent further damage that can lead to bigger health problems down the road. In fact, 1 in 5 Americans will develop skin cancer by the age of 70—and many of those due to the damaging effects of UVA rays.

What Do the SPF Levels Mean?

Okay, we’ve answered “what is sunscreen SPF”, but you might be confused when you realize that there are a variety of different SPF levels available. With so many options, it's hard to know which one is best. What is SPF in sunscreen, and what does the SPF number mean?

While we briefly touched on SPF levels, let’s take a closer look to see what those numbers really mean.

Here is a quick breakdown of SPF levels that can help you better understand:

  • SPF 15 - this is the lowest SPF you can find and it blocks about 93% of UVB rays
  • SPF 30 - this is the standard, recommended amount and it blocks about 97% of UVB rays
  • SPF 50 - this level provides stronger protection and blocks up to 98% of UVB rays
  • SPF 100 - this is the highest level of protection available, which blocks up to 99% of UVB rays

With this in mind, you’ll have more insight into how SPF works so you can choose the right sunscreen for you. No matter what SPF you select, it’s essential that you reapply every two hours—at least—and follow proper use instructions.

 Image of a bottle of sunscreen with an SPF 50+ label sitting on the sand.

Is SPF 30 or SPF 50 Better?

According to the Skin Cancer Foundation, SPF 30 or higher is generally recommended. However, those who are at high risk of skin cancer, have fair skin, or other conditions impacted by the sun may want to consider a higher level of SPF, such as SPF 50.

As such, Colorescience offers a wide variety of mineral sunscreens with SPF 50.

What About SPF 100?

Many people who consider buying SPF 100 often believe that, since it's more than double the recommended SPF level, it provides all the protection they need. This may lead to a false sense of security and lack of reapplication—which could result in skin damage.

While SPF 100 does provide somewhat greater protection, it must be reapplied as often as sunscreen with lower SPF. If you do choose to use a sunscreen with SPF 100, it’s important to ensure you’re covering all exposed areas and practice consistent reapplication.

This is especially the case if you’ll be swimming or sweating because getting wet can cause the sunscreen to wash off your skin, meaning it’s no longer acting as a barrier against the sun. So, whether you opt for a product with an SPF of 30 or 100, be sure to reapply it every two hours to ensure ongoing protection.

Which SPF is Best for Your Face?

The skin on your face is especially delicate and as such, prone to sun damage and signs of aging

When choosing a sunscreen for your face, you should typically opt for SPF 30 or higher. An SPF of 30 or higher is recommended for facial use because not only does it protect the skin from becoming burned, but it also impedes the sun from accelerating aging on the face.

Colorescience creates mineral sunscreen that’s chemical-free and safe for all skin types. Since your skin is especially sensitive in this area, it’s important to use products that are gentle, which is why options like brush-on mineral sunscreen that’s easy to apply make for an excellent solution.

Properties Sunscreen Should Have

What Factors Can Impact the Level of SPF You Need?

There are many factors that can impact the level of SPF you need, and these factors must be taken into consideration before making a final decision.
Some of the things you should keep in mind when selecting the right SPF include:

  • The amount of sunscreen you typically apply
  • How much you sweat
  • Your skin type
  • Whether you will be swimming or not

How Do You Find a Sunscreen with the Right Level of SPF?

If you're not sure how to find a sunscreen with the right level of SPF, there are a few things to look for:

  • SPF 30 or higher
  • Broad-spectrum protection
  • Chemical-free formula

Colorescience offers a variety of options that meet this criterion, including:

Browse our selection of these sunscreens and more to find the right option for you.

Two women at the beach on a sunny day sharing sunscreen with SPF

What is Broad Spectrum Sunscreen?

As we mentioned, SPF really only refers to protection against UVB rays—but those aren’t the only rays that may be doing you harm. UVA rays cause long-term damage like aging and wrinkles, and can do a lot of harm before your skin burns. The fact of the matter is that protection against only UVB rays just isn’t enough. That’s where broad-spectrum sunscreen comes in.

Broad-spectrum sunscreen (also known as full-spectrum sunscreen) protects against both UVA and UVB rays. And, frankly, it’s a must. In order for a sunscreen to be considered “broad-spectrum”, its UVA protection must be proportionate to its UVB protection. As SPF and therefore UVB protection increases, as must UVA protection.

How Should I Apply Sunscreen?

Remember when we said that sunscreens only provide the labeled level of SPF when applied “exactly as directed”? Let’s talk more about what that means.

The first thing to remember when applying your sunscreen is that you’re probably not applying enough. Experts estimate that most people only apply between 25% and 50% of the recommended amount. SPF tests are based on the presence of 2 milligrams of sunscreen for each square centimeter of the skin’s surface.

Woman applying sunscreen to another woman’s back at the pool.

In simpler terms, that equates to roughly a quarter-sized dollop for your face and a shot glass worth for your body. Consider SPF face primer and additional SPF products for additional face protection. Be sure to get very exposed areas, including your neck, ears, nose, and the tops of your feet.

Don't forget to cover your lips and consider using SPF lipstick. If your sunscreen is aerosol, that measurement isn’t quite as simple. Aerosol sunscreen is much harder to control, as breezy environments and improper application can leave your skin susceptible.

Reapply, Reapply, Reapply

Here’s the thing about applying sunscreen: just doing it once simply isn’t enough. Reapply your sunscreen every 90 minutes. If you’ve been doing a lot of physical activity, sweating, swimming, or towel drying yourself, reapply sunscreen immediately and consider sports sunscreen for total protection.

Remember that sunscreen isn’t only a must on sunny days. Whether sunny or cloud, rain or shine, sunscreen is a vital part of your daily routine.

Protect Your Skin with Sufficient SPF

Now that you have the answer to “what is SPF in sunscreen?”, you can make more informed purchase decisions that help protect you better. With the right SPF—and proper sunscreen practices, of course—you can enjoy the sun with peace of mind.

Shop Colorescience today to find a mineral sunscreen that’s equal parts safe and effective for use by everyone in your family.