The SPF value on a sunscreen pack and terms such as “broad spectrum” and “water resistant” tell you what the protection works against and under which conditions. A high SPF does not mean protection against UVA, and “water resistant” does not promise unlimited resistance in water.
In short: SPF (sun protection factor) shows protection against sunburn, which means mainly against UVB rays. According to the AAD, SPF 15 filters out 93% of UVB rays and SPF 30 filters out 97%; no value filters them all out. UVA protection is indicated on the label by the term “broad spectrum”. “Water resistant” describes 40 minutes of effectiveness in water and “very water resistant” 80 minutes. The WHO recommends protection when the UV index is 3 or above.
What is SPF, and what does it measure?
SPF (sun protection factor) is the level of protection a sunscreen provides against sunburn. According to the US Food and Drug Administration (FDA), each product is tested: the amount of UV needed to cause sunburn with the product applied is measured against the amount needed without it, and the product is given an SPF value accordingly. Because the test measures sunburn, SPF mainly reflects UVB protection; this is why the American Academy of Dermatology (AAD) suggests thinking of it as a “sunburn protection factor”.
What is the difference between UVA and UVB?
The AAD describes UVB as the burning rays and UVA as the ageing rays; a product that protects against both is labelled “broad spectrum”.
| Feature | UVB | UVA |
|---|---|---|
| AAD definition | Burning rays | Ageing rays |
| Where to look on the label | SPF value | The term “broad spectrum” |
| Common misreading | Assuming a high SPF also means UVA protection | Thinking every sunscreen protects against both types of rays |
According to the AAD, protection against both types of rays helps prevent sunburn and premature skin ageing (age spots appearing early, wrinkles, sagging). Not all the light from the sun is UV; we cover the effect of visible light on the skin in a separate article.
SPF 30 or SPF 50? Is SPF 30 enough?
The minimum the AAD recommends is 30; according to the FDA, higher SPF values provide more sunburn protection up to 50. The FDA's wording contains no separate comparison for values above 50; “50+” on a label indicates that the value is 50 or higher.
| SPF | UVB filtered out | Note in the official source |
|---|---|---|
| 15 | 93% of UVB (AAD) | The lowest value the FDA recommends, together with UVA protection |
| 30 | 97% of UVB (AAD) | The lowest value the AAD recommends |
| 50+ | No figure given in the source | FDA: values rising up to 50 provide more sunburn protection |
A high value does not mean you can skip applying enough or reapplying. According to the AAD, people who get sunburnt have usually not reapplied or have applied too little. We explain the amount needed for the face and how often to reapply in our article how much sunscreen to apply.
How do you read a sunscreen label?
Look for four pieces of information on the label:
- SPF value: the level of protection against sunburn, that is, against UVB.
- “Broad spectrum”: protection against both UVA and UVB. According to the FDA, products in the US that do not carry this term, or whose SPF is below 15, carry a warning stating that they have not been shown to protect against premature ageing and long-term sun damage.
- Water resistance: “water resistant” or “very water resistant”; the times are given in the next section.
- Active ingredients: sunscreens containing only titanium dioxide, zinc oxide or both are physical (mineral), those containing neither are chemical, and those with ingredients from both groups are hybrid sunscreens.
According to the AAD, the terms “broad spectrum” and “SPF” come from the FDA's testing standards; label wording may differ on products sold in other countries.
How long does water-resistant sunscreen last?
40 or 80 minutes, depending on the label. According to the AAD, a “water resistant” product stays effective for 40 minutes in water and a “very water resistant” product for 80 minutes; testing is required for these descriptions. Reapply such a product every 40 or 80 minutes when swimming or sweating; even if your skin stays dry, do not leave more than two hours between applications.
No sunscreen is completely waterproof; sweat and water wash the product off the skin. This is why the FDA no longer allows the claim “waterproof” and requires every label to state when to reapply.
What is the UV index, and at what level do you need sunscreen?
Sun protection is needed when the UV index is 3 or above. According to the World Health Organization (WHO), the index shows the level of UV radiation; the higher the value, the sooner damage to the skin and eyes can occur. The value announced is the day's peak UV level, and in many countries it is published along with the weather forecast.
| UV index | WHO recommendation |
|---|---|
| 0–2 | No special precautions needed under normal conditions |
| 3–7 | Shade around midday; clothing, sunscreen and a hat |
| 8 and above | Avoid being outside around midday; shade, clothing, sunscreen and a hat are a must |
Our guide to sunscreen in winter covers how UV reaches the skin in winter and in cloudy or snowy weather, and how sunscreen fits into a winter routine.
What do the labels of s'hevec sun products say?
The protection value of s'hevec sun products is SPF 50+, described on the pack as “very high protection”; for example, Just Protected From Sun SPF 50+ Hybrid Sunscreen, with its fluid texture, is used as the last step of the morning routine. The differences in texture, finish and when to use each product, along with the distinction between mineral, chemical and hybrid filters, are brought together in our guide to hybrid sunscreen. You can find all the products in our collection of SPF 50+ sunscreens.
The general label terms explained above are not claims for s'hevec products; a product's claims are limited to what is stated on its pack and product page.
Who should take care?
- Babies: the FDA does not recommend sunscreen for babies under six months; it advises keeping them out of the sun between 10:00 and 14:00 and using protective clothing if needed.
- People with lighter skin: according to the FDA, they may absorb more solar energy under the same conditions and burn more easily.
- People with darker skin: according to the AAD, the darker the skin tone, the greater the risk of UV and visible light causing dark spots; the AAD recommends shade, protective clothing and a tinted sunscreen containing iron oxides; this is the AAD's general recommendation.
- Sensitive skin: the AAD recommends physical (mineral) sunscreens. Before first use, do a patch test on the inner forearm.
- Pregnancy and breastfeeding: If you are pregnant or breastfeeding, or have a skin condition, consult your doctor before use. To choose a filter, show your doctor the ingredient list on the label.
When should you see a doctor?
See a doctor if you think your skin has developed sun damage, or if you need to apply sunscreen to a baby under six months. According to the AAD, a dermatologist can examine your skin and give advice; according to the FDA, babies of this age have a higher risk of side effects such as rash than adults.
Frequently asked questions
Does the SPF value tell you how long you can stay in the sun?
No. According to the FDA, SPF relates to the amount of sun exposure, not to time; the idea that someone who burns in one hour can stay in the sun for 15 hours with SPF 15 is not correct.
What does “sport” on the label mean?
According to the AAD, the FDA has not defined this term; it usually indicates that the product stays on wet skin for 40 or 80 minutes. For the exact time, look for the term “water resistant”.
Why does sunscreen lose its effectiveness during the day?
According to the AAD, sunscreen stays on the skin only for a limited time: the sun's rays break down some products, while others clump and lose their effectiveness. This is why you reapply every two hours when outdoors, and after towelling dry.
Can you use expired sunscreen?
It is not recommended. The AAD lists using expired product among the common reasons people get sunburnt. The FDA also recommends not leaving the container in direct sun, so that the product stays effective.
Can you use sunscreen during pregnancy?
If you are pregnant or breastfeeding, or have a skin condition, consult your doctor before use. To choose a filter, show your doctor the ingredient list on the label. The measures the WHO recommends, such as shade, a wide-brimmed hat and protective clothing, apply whichever product you choose.
Does sunscreen block vitamin D absorption?
Sunscreen may affect the production of vitamin D in the skin, not its absorption. According to the AAD, sun protection can reduce the skin's vitamin D production; the AAD recommends that healthy adults get vitamin D from foods that contain it or are fortified with it. The WHO also states that people who get very little sun should consider oral vitamin D supplements, and that sunbeds are never an option for vitamin D. If you are concerned about your vitamin D levels, talk to your doctor about the options.
Sources
- American Academy of Dermatology (AAD). Understand sunscreen labels.
- U.S. Food and Drug Administration (FDA). Sunscreen: How to Help Protect Your Skin from the Sun.
- World Health Organization (WHO). Radiation: The ultraviolet (UV) index.
- American Academy of Dermatology (AAD). How to apply sunscreen.
- American Academy of Dermatology (AAD). Sunscreen FAQs.
- World Health Organization (WHO). Ultraviolet radiation (fact sheet).
This content is for information only and does not replace medical advice. s'hevec products are cosmetic products and are not intended for medical treatment. It was prepared by the s'hevec Team on the basis of the s'hevec product data library and the sources listed above.
