How to choose the right sunscreen

Every spring, as soon as the warm weather returns, the same question comes back: how do you choose the right sunscreen? With all the information printed on a tube, it is not always easy to find your way. What do the SPF number and the UVA and UVB labels on the packaging actually mean? How do you know which protection really suits your skin? These questions come up every year, and they deserve clear answers.

Good news: choosing a suitable sunscreen is not complicated once you know a few simple markers. Let's look together at what the information on a tube means and how to use it to make an informed choice, for your skin and for your children's.

What does the SPF number actually tell you?

The most visible number on a sunscreen tube is the SPF. Those three letters stand for Sun Protection Factor. This index measures how well the cream protects against UVB rays, the ultraviolet B rays that reach the surface of the skin and cause sunburn.

But what does the number that follows, a 30 or a 50, really mean? In theory, it tells you how much longer your skin can stay in the sun before burning. With an SPF 30, it takes about thirty times longer than unprotected skin. With an SPF 50, about fifty times longer. The SPF 50+ label stands for the highest level of protection on the market, the one recommended for fair skin and for children.

So you might think an SPF 50 protects far more than an SPF 30. In reality, the difference is smaller than most people believe. The clearest way to see it is to look at the share of UVB rays each cream actually blocks. An SPF 30 blocks around 97 percent, an SPF 50 around 98 percent. The gap between the two is therefore very small.

So which factor should you choose? For fair or sensitive skin, for children or for a long day outdoors, an SPF 50+ remains the safest choice. For everyday use in the city, an SPF 30 is plenty. Above all, remember that the amount you put on your skin matters as much as the number printed on the tube.

UVA rays: the other threat to protect against

The SPF only tells you about UVB. Yet the sun also sends a second type of ray, the UVA, or ultraviolet A. They are less well known, but just as important. Unlike UVB, they do not cause a visible sunburn. They penetrate deeper into the skin and are present all year round. You will even find them on cloudy days or behind a window, because they also pass through glass. These are the rays that speed up skin ageing and contribute to long-term risks. Precisely because they work silently, with no sunburn to sound the alarm, their effect on the skin over the years was underestimated for a long time.

A good cream must therefore protect against both UVB and UVA. To check this, one marker is enough. Look for the letters UVA inside a circle, printed somewhere on the tube. It is a European standard. Its presence guarantees that the UVA protection reaches at least a third of the SPF stated on the tube, which ensures balanced coverage against both types of ray. If that circle appears nowhere, it is better to choose another cream.

Mineral or organic filters: which should you choose?

There are two main families of sun filters on the market. Both are effective, and the choice depends mainly on your skin. Neither should be ruled out on principle.

Mineral filters stay on the surface of the skin and reflect the sun's rays, a little like a mirror. They suit sensitive skin and young children particularly well, because they start protecting the moment you apply them, without the waiting time that some other formulas require. They are also very well tolerated. They used to leave a slight white film, which is far less visible in recent formulas.

Organic filters absorb UV rays. They are also called chemical filters. Their texture is often lighter and easier to spread, which helps you apply enough. They suit skin with no particular sensitivity, which is why you find them in a large share of the creams sold in shops, from body sprays to everyday face care.

The right choice therefore depends on your skin and your habits. A mother whose child has very reactive skin will lean towards a mineral filter. Someone who dislikes a greasy feel will prefer a lighter organic one. The best cream is still the one you actually apply, because you like its texture.

How much sunscreen to apply, and when?

This point is crucial. Yet most people almost always overlook it. Protection factors are measured in a laboratory with a precise amount of cream. In everyday life, we often use two to three times less than needed. The reasons: fear of a greasy finish or a lack of time in the morning. An SPF 50 applied in too small a dose ends up protecting barely like an SPF 20. The dose matters at least as much as the factor you choose.

The recommended amount is easy to remember. For the face and neck, count about one teaspoon of cream. A handy trick helps you picture it: the two-finger rule. Lay the cream along the full length of your index finger, then your middle finger, which gives the right dose. This dose applies to a single application, in every outdoor situation. It holds just as well for a long day at the beach as for a quick errand in town. For an adult's whole body, count the equivalent of a shot glass, roughly thirty millilitres.

Timing matters too. Apply the first layer about twenty minutes before going out, so the cream can form a real protective film on the skin, then reapply every two hours during direct sun exposure. The reason for this frequency is simple: UV filters break down naturally over the hours, under the effect of sweat, sebum, and the rubbing the skin goes through during the day. Also remember to reapply after every swim and after heavy sweating, because that is when most of the cream comes off.

The spots people often forget

Even when we apply cream, we often forget certain spots. The ears and the back of the neck catch a lot of sun, as do the tops of the feet and the edges of the lips. For the lips, a sun stick does the job nicely. Also think about protecting children's necks, very exposed when they play leaning forward. A wide-brimmed hat and an anti-UV tee-shirt take care of much of the problem with no effort.

What do the other labels on the tube mean?

Beyond the SPF number and the UVA circle, other labels appear on the packaging. Some reassure more than they inform. It is worth knowing what they really mean. The words "total sunblock" are now banned in Europe, because no cream blocks all the rays. If you still see them on an old tube, be wary. The words "long-lasting protection" do not exempt you from reapplying, since the cream stays effective for about two hours. The words "for sensitive skin" are governed by no official rule, which means two creams making the same claim can hide very different formulas once you read the list of ingredients. To judge for yourself, look instead at whether it contains mineral filters and no added fragrance. Finally, "water-resistant" means the cream holds up for a certain time in the water, but that you need to reapply after swimming.

None of this is really worrying. It is simply about learning to read a tube of cream, a little like learning to read a food label at the supermarket.

Does sunscreen have an expiry date?

Yes, sunscreen does not keep indefinitely. On the tube, a small open-jar symbol shows the number of months the cream stays effective once opened. After that, the filters protect less well. Heat also damages the cream. A tube left in full sun all day on the sand, then packed away still warm in a closed bag, loses part of its effectiveness with nothing to show for it to the eye. Keep it in the shade instead, in your bag. For children's skin, it is better to start each summer with a fresh cream.

Is sunscreen enough on its own?

This is probably the most important part of this article. Sunscreen remains a valued ally for enjoying the sun with peace of mind. And yet, as we have seen throughout these lines, it has its limits.

The first has to do with quantity. An SPF 30 or an SPF 50 often protects less than expected, because most people apply well below the recommended dose. The second has to do with real conditions. Sweat and swimming take away a good part of it, as does simply patting yourself with a towel. 

This is where clothing comes in. An anti-UV swimsuit or a long-sleeved tee-shirt certified UPF 50+ stops more than 98 percent of the sun's rays. The UPF label is to fabric what the SPF is to cream: it tells you the share of UV the garment lets through. Such a garment does not wear off and does not need reapplying, which protects large areas of the body continuously, from morning to evening, without you having to watch the clock or call the children back every two hours for another layer.

The cream then keeps its full role on the face and hands, the spots the garment leaves bare. So the best protection is not about choosing between clothing and cream. It comes from combining them: the garment covers the large areas without you having to think about it, and the cream takes over on the rest.

Frequently asked questions

SPF 30 or SPF 50: which should you choose? Both protect well when applied in sufficient quantity. SPF 50 is recommended for fair or sensitive skin and for long days in the sun, children included. SPF 30 is enough for everyday use in the city. Here again, regularity matters more than the gap between the two numbers.

SPF, UVA, UVB: what do these letters mean? SPF (Sun Protection Factor) measures protection against UVB, the rays that cause sunburn. UVA rays penetrate deeper into the skin and contribute to its ageing. A good cream protects against both, which the UVA-in-a-circle symbol guarantees.

Do you still need cream under anti-UV clothing? Under a garment certified UPF 50+, it is not necessary. It already protects the areas it covers well. Cream stays useful on the face and hands, the spots the garment leaves bare.

Is last year's cream still good? It depends on when it was opened and how it was stored. A tube opened more than a year ago, or left in full sun, has probably lost some of its effectiveness. When in doubt, it is better to buy a new one, especially for children's skin.

So, how do you choose the right sunscreen?

When it comes time to choose, a few simple criteria are enough. First check that the cream offers broad-spectrum protection: the UVA circle should appear on the tube, next to an SPF suited to your skin. Then pick a texture you genuinely like. Whether it is mineral or organic matters little, as long as it makes you want to apply it often and in a good amount. Finally, check the shelf life, especially for children's skin. Nothing more complicated than that.

The rest comes down to a regular habit: a good dose, reapplied every two hours. And to make life easier, the most effective thing is to cover the skin. An anti-UV swimsuit or a long-sleeved tee-shirt certified UPF 50+ protects large areas of the body with no cream and no reapplying, from morning to evening. A wide-brimmed hat completes it all for the face and neck. The best protection is still the one you actually wear.