A Simple Guide to SPF: What It Is, How It Works, and Which One Is Best for You

Guide to SPF - woman applying natural sunscreen at the beach


Picking the correct SPF is not always an easy task. Should you wear a 30 or 50 protection? Which one is more adapted to your face? You don't want to put chemicals on your baby, but how to protect him from the sun? And what about your skin sensitivities?

If you're reading this, chances are it's because one of these questions has popped into your mind. You know how much the sun can be damaging to your health and skin, yet choosing the right protection is simply a headache. 

Well, today, we want to simplify this process for you. By drilling down into the SPF - what it is, how it works, and where it goes - we want you to be fully empowered and informed so that you can pick out the protection that works best for you. 

What Is SPF, and How It Works

The term SPF stands for Sun Protection Factor. Simply put, it's a measure used to inform you of a sunscreen's ability to protect your skin. Unfortunately, a simple look at your chemist sun-shelf doesn't make it super explicit. 

While it's easy to assume that an SPF number relates to how strong or powerful protection can be, an SPF mark actually gives you an idea of how long you can stay in the sun - without getting burnt. So when you encounter several digits such as SPF 15, 30, or 50, this relates to the length of time you can spend in the sun. 

The Coppertone Solar Research Center came up with a simple calculation to understand the impact of SPF on our skin. Let's say you get a sunburn after 20 minutes without sunscreen. If you apply an SPF 30, you will be able to stay 30 times longer under the sun. Alternatively, if you use an SPF 50, it will be effective 50 times longer. 

However, it's important to note that this calculation can significantly vary depending on various factors - which will touch on later on.

Along with SPF, you might have heard of the terms UVA and UVB's. Those are the two primary types of ultraviolet that impact our skin. UVA stands for UV-ageing. As you might have guessed, this type of UV penetrates deep into your skin layer and influences fine lines, wrinkles, and dark spots. Along with that, you have the UVB, which stands for UV-burning. They affect only the surface layer of your skin, causing sunburn at best and melanoma moles at worst. Most SPF, no matter the number, only creates protection from UVB. In order to protect yourself from both UV types, you will need to favour a sunscreen labelled broad-spectrum.


guide to spf - woman holding natural sunscreen before surf

Choosing the Right SPF for You

This is probably not the answer you expected, but there is no right or wrong SPF for you. Choosing an SPF really comes down to your needs - or should we say laziness?. 

Each SPF will offer the same UVB protection to your skin. The trick lies in applying sunscreen generously and regularly. It's been shown that an SPF 30 applied generously was more effective than an SPF 50 spread thinly or not frequently enough. 

Other factors can also be considered when it comes to UV protection, such as your age, skin type, and environmental factors. You may burn more quickly than your friends or have sensitive skin. You might also be tanning during the sun peak hour or heading for a swim every 20 minutes. Taking these into account will give you an idea of how much and how many times sunscreen should be applied. 

So when we talk about an SPF 30 protecting you 30 times longer, your unique factors will tend to reduce this number quickly. In order to stay protected, you should consider how long it takes for your skin to become red. For a baby, this might be 10 minutes, and therefore, sunscreen should be applied every hour or after a swim. On the other hand, an adult with naturally tan skin might last more than 1 hour without getting red, so re-applying sunscreen every few hours might be enough. 


Each SPF is created equal. What makes them different will depend first, on your unique tolerance to the sun and then, on the environment you use it in. The key is to note how your skin reacts to the sun and then protect it accordingly. Applying a broad-spectrum sunscreen generously and regularly will actively keep you safe from UVA and UVB. The SPF number is up to your preferences.

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