SPF 30 or SPF 50? What the number on sunscreen really means
Natali Profumeria · 1 min read · November 1, 2026
On the packaging of every sunscreen, there is a number: 15, 30, 50, 50+. It is the first piece of information we look at and, often, the one we understand the least.
What SPF measures
SPF stands for Sun Protection Factor. It measures how well the product protects against UVB rays, which cause redness and sunburn. The higher it is, the better the skin is protected from sunburn.
In Europe, sunscreens are divided into four categories: low (6–10), medium (15–25), high (30–50), and very high (50+).
Between 30 and 50, the difference is small but counts
SPF 30 filters about 97% of UVB rays, while SPF 50 filters about 98%. That may seem like very little, but it means that with SPF 50, almost half as many rays reach the skin as with SPF 30. For people with fair skin, for children, and for those spending many hours in the sun or in the mountains, high protection makes a difference.
No sunscreen protects 100%
This is why in Europe terms like "total protection" can no longer be used. Even the best sunscreen only works if you apply the right amount and reapply it often: most people use less than half of what is needed, which significantly reduces the actual SPF.
Protection from UVA rays
The SPF number refers to UVB rays. For UVA rays, which age the skin and penetrate even through clouds, look for the "UVA" symbol inside a circle: it indicates that the UVA protection is adequate relative to the SPF, as recommended by the European Union.
Frequently asked questions
What is the difference between SPF 30 and SPF 50?
SPF 30 filters about 97% of UVB rays, while SPF 50 filters about 98%. With SPF 50, almost half as many rays reach the skin as with SPF 30: for fair skin, children, and many hours in the sun, it is the safer choice.
Is there total protection?
No: no sunscreen blocks 100% of rays. This is why the term "total protection" is no longer allowed in Europe.
Does SPF also protect against UVA rays?
The SPF number measures protection against UVB rays. For UVA protection, look for the "UVA" symbol in a circle on the packaging.