Sun Protection 101: What SPF Should You Use?

To choose a sunscreen that will give you the right protection, you need to sift through a wide range of different product types as well as their SPF labels, going from 5 to 100+. But what do these numbers actually mean and is the bigger number always better?

April 18, 2022 6 minutes read
Young woman wearing sunscreen with SPF 30

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If you're into skincare, you probably know by now how important it is to use sunscreen all year round (and if, by some chance, your daily routine doesn't include an SPF, it's never too late to change your habits). However, you might ask yourself – But there are so many different products with different SPFs? So, which one is right for me?

Ideally, sunscreens with higher SPFs should give you better protection, right? Well, yes, in theory, but in reality, things are a bit more complicated than that. This article explores what the experts say about how much SPF you need in your sunscreen.

Understanding SPF: What Do All Those Numbers Mean?

many different sunscreens with various SPFs

SPF, or the Sun Protection Factor, is a number that calculates the protection that a product is supposed to provide. In other words, it measures the safe sun exposure time before getting a sunburn.

So, for example, if your skin needs about 10 minutes to get a sunburn without sunscreen, then sunscreen with an SPF 15 should offer you sun protection that is 15 times greater. Therefore, the calculation would be – 15 times 10 is 150 minutes, meaning an SPF 15 gives you 150 minutes of sun exposure before a sunburn; an SPF 30 gives you 300 minutes of safe sun exposure, and so on.

And ideally, a sunscreen with an SPF 15 should give you the whole 2 hours and 30 minutes of safe time in the sun, but only if you apply 2 mg of the product per one square cm of the skin, as recommended. In reality, research suggests that an average sunscreen user will only apply a quarter of the recommended amount, which is about 0.5 mg per square cm.

In addition, studies show that there's not much difference between an SPF 15 and those much higher in terms of sun protection:

So, Does SPF in Sunscreen Matter?

woman applying sunscreen SPF 30 on her legs

To some extent, SPF in sunscreen still matters as those with higher ones offer slightly better protection. Therefore, according to AAD (the American Academy of Dermatology Association), you should go for sunscreens with an SPF of at least 30.

In the end, it's safe to say that you're safe with those that have SPF between 30 and 50, but you shouldn't fall for those much higher than that – they can only offer a false sense of security and not much better protection. The manner of application also matters – apply your sunscreen liberally (approximately one shot glass of product per one application for a whole body) and reapply it every two hours.

However, when choosing the right sunscreen for you, SPF shouldn't be your only focus. There are other factors you need to consider:

Choose broad-spectrum sunscreens: There are two types of UV rays that we need to be worried about – UVB causing sunburn and UVA causing skin aging and cancer. SPF covers only UVB rays. Therefore, you need to choose those products labeled as broad-spectrum, covering both UVA and UVB rays.

Pay attention to the type of sunscreen: There are two main sunscreen categories, chemical sunscreens and mineral sunscreens, the latter also called sunblocks. Mineral sunscreens contain ingredients (or inorganic agents) such as titanium dioxide and zinc oxide, which act as a skin shield, reflecting UV rays. These ingredients work against both UVA and UVB rays.

On the other hand, we have chemical sunscreens containing a wide range of ingredients or organic agents that absorb sun rays. However, not all of these ingredients are effective against all the damaging UV rays. And so, there are ingredients such as octinoxate, cinoxate, octisalate, homosalate, and trolamine salicylate that work only against UVB rays or skin burning.

In contrast, other ingredients, such as avobenzone and meradimate, work only against UVA rays, protecting you from skin cancer and skin aging, but not against burning. And finally, there's a group of organic compounds that are effective against both UVA and UVB rays, such as oxybenzone, dioxybenzone, sulisobenzone, octocrylene, and ecamsule. Therefore, if you decide to go for a chemical sunscreen, make sure they contain the right combination of ingredients to ensure broad-spectrum sun protection.

Also, be mindful that some of these ingredients aren't eco-friendly. For example, Oxybenzone, Octinoxate, Avobenzone and Octocrylene are banned in Hawaii (and later in the U.S. Virgin Islands, Aruba, Key West, and Marshall Islands) because of their toxic effect on coral reefs, on which about a quarter of all marine life depends. So, if you want to be kind to your skin as well as your environment, be sure to choose chemical sunscreens that are labeled reef-safe.

Furthermore, there are sunscreens in lotion and spray form. Since it's much easier to measure a proper amount of lotion sunscreens, we would always recommend choosing those instead of spray-ons. However, if you're looking for a more convenient method of reapplying your sunscreen over makeup, for example, you could use a spray sunscreen but make sure to apply it properly – hold the nozzle close to your skin and make sure to spray long enough to leave an even sheen on your skin.

UVA and UVB sun rays infographic

Avoid ingredients that cause photosensitivity: Ingredients such as hydroquinone, AHAs (most commonly glycolic acid), and retinoids (including retinol, tretinoin, retinaldehyde, and retinyl palmitate) increase your skin's photosensitivity, which means they make it more prone to sun damage.

For this reason, it's essential to use skincare products with these ingredients as a part of your nighttime routine, avoid applying them in the morning, and avoid using sunscreens that contain them.

Go for water-resistant products: To ensure the best protection possible, choose water-resistant sunscreens, as these will likely stay on your skin even after sweating. Still, it would be best if you reapplied these after two hours as well. However, there are no completely waterproof sunscreens. Therefore, if you're at the pool or beach, reapply your sunscreen right after swimming.

Use SPF of at least 30 even if you have a darker skin tone: Indeed, people with fair skin tones and freckles generally burn more quickly when exposed to the sun. Nevertheless, every skin type, including darker skin tones, can suffer significant damage from UV radiation. Therefore, choose sunscreens with an SPF 30, at least, no matter your skin type and tone.

Other Sun Safety Tips

Besides choosing the right sunscreen and reapplying it often, the best and most effective defense against sun damage would be a combination of several other factors as well, such as:

sun protection tips infographic


Even though an SPF is still the primary information about the efficacy of sunscreen, other factors such as the regularity or reapplication as well as the applied amount of a product play an essential role in proper sun protection.

So far, we should understand that while important, the Sun Protection Factor or SPF shouldn't be the only criterion for choosing sunscreen. In addition to its SPF, which should always be at least 30, your sunscreen or sunblock should be broad-spectrum, water-resistant, and photostable.


Is it better to use SPF 30 or 50?

Sunscreens with an SPF 30 usually allow about 4% of sun rays to reach your skin (meaning they protect you against about 96% of UV rays). In contrast, sunscreens with an SPF 50 allow about 2% of UV rays to reach your skin, protecting you from about 98% of sun rays or slightly less. Therefore, there's not much difference between an SPF 30 and SPF 50. It's more important that no matter the SPF of your product, you apply it in the proper amount and reapply it every 2 hours.

Is SPF 15 or SPF 50 better?

If your skin needs about 5 minutes to sunburn without protection, a sunscreen with an SPF 15 protects your skin from burning 15 times longer (15 x 5 = 75 minutes). However, to get this level of protection, you need to apply the right amount of sunscreen (about 2 mg on 1 square cm of the skin). And since most people usually apply less, dermatologists often recommend using sunscreens with an SPF of at least 30.

Is SPF 50 harmful?

No, sunscreens with SPF 50 aren't harmful to your health. The only risk with sunscreens with higher SPFs is a potential false sense of security. If you spend hours in the sun but don't apply a proper amount of the product and don't reapply it every 2 hours, thinking the higher SPF will protect you longer, you're risking sun damage which may result in skin cancer later on.

What does PA ++ mean?

SPF label on your sunscreen usually refers to the protection against UVB rays, or, in other words, sun burning. On the other hand, the PA label indicates that the product also offers some protection against UVA rays, and you're most likely to find this label on Korean and Japanese products. And so, PA ++ means that the sunscreen offers moderate protection against UVA radiation, while PA +++ indicates higher protection.

Which rays are worse, UVA or UVB?

Unlike UVA rays, UVB rays don't penetrate the deeper layers of your skin and usually result in sunburn. On the other hand, UVA rays feel a bit less intense but can reach the innermost layers of the skin, causing DNA damage inside the skin cells and, potentially, skin cancer. Also, UVA radiation is present throughout the year, even in winter and on cloudy days. For this reason, dermatologists advise wearing sunscreen throughout the year (especially on the face, hands, lips, and other parts of the body that aren't covered with clothing).

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