Can you honestly say that you know what the SPF number on your sunscreen means? By that, we mean over and above the knowledge that a higher number needs more protection. If so, don’t worry. Many people are a bit fuzzy about the facts when it comes to what’s a safe sunscreen SPF for their needs.
We aim to help you out here by going over what the numbers actually relate to. So, if you have your notebook and pen ready, let’s get into it!
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Finding the Safe Sunscreen SPF for Your Needs
The good news is that identifying a safe sunscreen SPF for yourself is relatively simple, as it just requires a little knowledge. So, SPF essentially stands for Sun Protection Factor, and the number you see next to it on a bottle of sunscreen (15, 30, or 50) indicates the amount of time you can stay out in direct sunlight without burning.
In short, let’s say that it takes 20 minutes to burn in the sun without sunscreen. An SPF 30 sunscreen would allow you to stay out 30x longer – 600 minutes before you burn. If it were an SPF 50, that figure would go up to 1,000 minutes (50x 20 minutes).
SPF Numbers Are Not Linear in Blocking UV Rays
Time allowed in the sun is not the only difference between the various SPF levels. It also matters in terms of the amount of UVB rays that it stops, but it’s not as linear as you might expect. An SPF of 15 blocks 93%, with an SPF of 30 blocking 97% and an SPF of 50 blocking 99%.
You might expect an SPF 30 to block twice as many rays, but that’s not the case. They may seem like small differences, but for someone with sensitive skin, that extra 1-2% can be meaningful enough to consider a higher option.
“So, What’s Right For Me? How Do You Choose?”
It would be great if it were a simple answer, but as with many things, the right choice depends very much on the person using it and the conditions in which it’s being used. It breaks down a little like this:
- Your skin type plays a part—if you have fair or sensitive skin, you’ll probably need an SPF 50, whereas those with darker skin tones may be able to get away with an SPF 30 or even an SPF 15 for everyday use.
- What you’re doing outside matters—if you’re going out doing everyday things for a standard amount of time and you have normal, healthy skin, an SPF 30 is going to be more than enough. However, if you’re spending all day outside, you’re back to needing an SPF 50.
- What time of day you go makes a difference—the sun is much more intense between 10 am and 4 pm, which means you need more protection. Outside of these periods, the sun can still be harmful, but not to the same degree.
The Safe Sunscreen SPF Level Depends On You
As is evident, finding the right SPF level for your needs depends on three main factors: 1) your skin tone and health, 2) how long you’re going to be out in the sun and 3) how intense the sun is while you’re out. Before we finish, however, there’s something else we need to mention.
Everything we’ve talked about in this article depends on you reapplying the sunscreen you choose every two hours. If you don’t, and you stay out all day, all bets are off, and you’ll likely get sunburn either way.

