how to choose the right spf number for your needs and lifestyle

“30 or 50? 15 is definitely too low but where’s the catch if I go too high?”

I’m talking about SPF numbers. How the heck do you choose the one that’s right for you? Like, can you get away with a lower SPF if you don’t go to the beach or is it better to aim high in winter, too?

Here’s a quick guide to help you figure out the protection SPF numbers give you and how to choose the best one for your needs and lifestyle:

How Does SPF Work?

Nope, SPF doesn’t tell you how well a sunscreen protects you from UV rays. It tells you only how well it protects you from UVB rays.

In other words, SPF simply determines the amount of time you can stay in the sun without burning. Here’s an example. Let’s say your skin starts to burn after 20 minutes of unprotected sun exposure. If you use SPF 15, your skin will take 15 times longer to burn.

But even this is misleading. You see, when scientists determine SPF, they use a lamp that emits a constant stream of light. In real life, UVB rays are stronger in the afternoon and weaker in the early morning and early evening. So, even if you wear SPF 15 all day, it’ll take you way longer to burn in the early morning than in the early afternoon!

And that’s not even the whole story! UV filters get used up as they do their job. The more sunlight they’re exposed to, the sooner they degrade. You know what that means? There’s no way that SPF 15 is gonna last you 5 hours. At the beach, it becomes useless after 2!

WARNING: I’m gonna tell how to choose the right SPF number for you now. But make sure your sunscreen protects your from UVA rays as well. If you don’t know if your sunscreen provides adequate UVA protection, check out this post to find out.

Related: Do You Really Need To Reapply Sunscreen Every 2 Hours?


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SPF Under 15: Don’t Bother

It’s rare to find a sunscreen with SPF lower than 15. For a good reason: they don’t provide adequate sun protection. If you come across SPF 11 or something, it’s usually on foundations or tinted moisturisers. By all means, use them to even out your skin tone or moisturise your skin, but don’t expect any real sun protection from them. Cosmetics with SPF are NOT a substitute for sunscreen.

Related: Do Cosmetics With SPF Provide Adequate Sun Protection?

bioderma cicabio spf 50

SPF 15: Barely Enough For Winter Days

SPF 15 is the minimum recommended by derms for daily, casual wear.

FYI, casual wear doesn’t mean you can put your sunscreen on today or forget all about it tomorrow. Casual wear means “days when you’re not getting much sun exposure.”

You know what I’m talking about. It’s the middle of winter. The sun hides behind dark gloomy clouds. Maybe it makes a brief appearance, too.

Either way, you’ll barely see it. You get out of the car just to walk to your office or run brief errands. Who wants to be outside in this freezing cold?

On days like this, a SPF 15 is just about enough. It blocks a whopping 93% of UVB radiation. Sounds like a lot, doesn’t it? Until you realise that 7% of UV rays still make it past it and hurt your skin.

In winter, this ain’t a big problem, but in summer? You definitely need to up your sun protection then.

Related: Do You Need To Wear Sunscreen While Driving?

SPF 30-50: Best For Spring & Summer Protection

You may think there’s a huge difference between SPF 30 and SPF 50. Until you look at the real numbers:

SPF 30 blocks nearly 97% of UVB rays while SPF 50 98%. Who would have thought the difference was so minimal?

If the sun’s shining and you’re spending any time outdoors – even if it’s just taking your dog for a walk – or are sitting for hours near a big window, you need an SPF in this range.

SPF 30 is the one I choose for everyday wear even in winter (I’m just not comfortable with SPF 15). In summer, I up to SPF 50. Better safe than sorry, right?

Related: Do You Need To Wear Sunscreen Indoors Too?

SPF 50+: Better Summer Protection (But The Texture’s Worse)

The verdict’s out: the higher the SPF, the better sun protection you’re getting. SPF 50+ can block up to 99% of UV rays. As long as you’re careful with reapplication.

Here’s the deal: the higher the SPF is, the thicker and unpleasant the texture becomes. Makes sense. If you want to increase the SPF, you need to use a bigger dose of UV filters. And those are often oily/greasy.

So you apply a bit less. I mean, it’s SPF 100. I don’t need a generous dose, right?

Wrong! If you apply less than the recommended amount (1/4 of a teaspoon for the face and a small glass shot for the body), you’re reducing the SPF and compromising your protection.

You may also think you can get away with reapplying a high SPF less often. Again, wrong! Its UV filters still get used up.

Bottom line: with higher SPF numbers, there’s a trade off. They provide better protection if you’re religious with application. Skimp on that and all you’re left with is a false sense of security that leads to sun damage.

If you can tolerate the unpleasant texture and are willing to use it properly, SPF50+ is a great choice. If not, SPF 30/50 will do job just fine.

Related: Does SPF 100 Provides Better Sun Protection Or Just A False Sense Of Security?

The Bottom Line

Always go with the highest SPF your skin can tolerate and reapply it generously. Whatever you do, never go below SPF15. Low SPFs let the sun do too much damage.

What SPF number are you using? Share your picks in the comments below.