Sunscreen Math: Can You Add Up SPF?

Are you slathering on your sunscreen with SPF 30, moisturizer with SPF 20 and foundation with SPF 15 and thinking, “I’m getting SPF 65, awesome!”. Well, I’m sorry to be the bearer of bad news, but it doesn’t really work like that.

Unfortunately, layering sunscreens will not give you added SPF protection. That’s just a myth. You see, sunscreen ingredients don’t mix together to increase the SPF level, so each product you apply retains its own SPF. That means that, when you use several products with SPF, you end up only with the SPF of the highest sunscreen you applied.

Thus, in our example above, the level of SPF you end up with is 30. If instead, you apply sunscreen with SPF 15 and foundation with SPF 15, you end up with only SPF 15, not 30. I know, that’s a bummer! However, layering sunscreens is not completely useless.

While layering such products will not add up SPF, it may increase your overall coverage. Sunscreen needs to be applied to all skin areas exposed to the sun, but there’s always the chance you may inadvertently miss a spot. If you apply more products with SPF, that risk is lessened.

Do you stick to sunscreen only or do you apply several products with SPF every day?

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    • beautifulwithbrains says

      Socialite Dreams, that’s true. I guess because so many products contain SPF these days, we all tend to layer them, even if don’t do it on purpose. :)

  1. says

    I just stick to sunscreen though I have been using SPF moisturizer because I can get that into my hairline without it caking up and then I’ll blend some actual sunscreen into there and it works better (smoother application). Sometimes I use sunscreen for my brows (they’re a light black and taupe colors work best for filling them in) and sunblock for my face so that my brows don’t turn salt-and-pepper-grey on the days I don’t want to fill in my brows.
    I have a question! I am in higher altitude and will be hiking up mountains to even higher elevations. I’m currently at 6035 ft or 1839meters above sea level lol… and it’s so dry here and it’s quite harsh on my already dry skin not to mention the literally scorching sun on my pale skin. I’ve been applying sunblock and touching up through the hot, slightly sweaty days (sorry if that’s gross) and I’ve brought my UPF 50 hat and wear long pants but what can I do? I’m just looking for advice. I really don’t want to burn lol. I burn with sunscreen (not sunblock) on.
    <3 you are the person I trust and look up to!

    • beautifulwithbrains says

      Janessa, if you’re already applying sunscreen regularly and wearing protective clothing, I don’t think there’s anything more you can do unfortunately. If you still burn with the sunscreen you’re using, maybe you can try another one. The only other thing I can think of is to stay in the shade, but I know that’s not always possible.

      • says

        Okay, thank you so so much! You are the best! :] And I read your replies to other comments sometimes. You put all your heart into answering them! 😀

  2. says

    This is a good post to think about. Many people think that by layering they can increase SPF coverage when nothing is further from the truth. I read somewhere once that the tip to bear in mind is that the highest SPF product you apply is the one that counts. The rest don’t. So I go with a high SPF sunscreen and I don’t mind or bother if other products (makeup/skincare) contain no SPF because I’m already protected :)
    Paris B´s last blog post ..Getting silly with Silly Lips Lipbalm : Tasty lipbalm in unique, eye-catching packaging!My Profile

    • beautifulwithbrains says

      Paris, that’s so true. Like you, I always use sunscreen too, so I don’t really mind whether the other skincare products I use contain SPF or not. I think that, while layering products may slightly increase your coverage (ie less chance to miss a spot), if you’re careful with application that shouldn’t be a problem anyway.

    • beautifulwithbrains says

      Xin, unfortunately most people think so and it’s a shame. Glad you’ve found out the truth and are using sunblock now instead than reliable solely on cosmetics.

  3. says

    I also heard that we shouldn’t mix products with SPF as they may interfere with each other and therefore give us less protection. So many sources and so many different opinions, it’s really hard to get some conclusion :(

    • Gio says

      Pink, that’s only partly true. Zinc oxide and titanium dioxide can degrade avobenzone, making it less effective. But that just means that you need to reapply the sunscreen more often. Or better yet, avoid using this combination. Hope this helps. :)

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