What is good sunscreen?

If you work outdoors, or enjoy the sun, your skin is taking a daily ultraviolet dose. A reliable sunscreen is the most effective single thing you can do about it. With a crowded shelf to choose from, here is what is worth reading on the label.

1. Provides both UV-A and UV-B protection

Look for the words broad spectrum. This is the single most important check, because the SPF number describes UV-B only. UV-B (about 290–320 nm) is the burning band and drives most direct DNA damage; UV-A (about 320–400 nm) penetrates deeper and drives photo-ageing through reactive oxygen species. Both contribute to skin cancer risk; the older shorthand that UV-A only ages you and UV-B only burns you is too neat. A product can carry SPF 50 and still filter UV-A poorly unless it is tested as broad spectrum.

UV-A also matters year-round. Cloud attenuates it to about the same degree as UV-B, so overcast days still deliver a meaningful dose, and unlike UV-B it passes through ordinary window glass, so it reaches you beside windows too.

2. Buy from a manufacturer you can check

Sunscreen is a regulated product, and the thing worth verifying is not brand reputation but whether the label carries a real, tested SPF and broad-spectrum claim. Read reviews for how a product feels (that predicts whether you will reapply it) and read the label for what it protects against. Price is a poor proxy for either.

3. Check water resistance of the sunscreen

If you will swim or sweat, choose a water-resistant product. Note what the claim means: water resistance is tested for a stated duration, either 40 or 80 minutes of immersion, and the label must say which. It is not permanent, and "waterproof" is not a claim US labels are allowed to make. Reapply after swimming, after towelling, and roughly every two hours regardless.

4. Active ingredients for sun protection

The actives are the UV filters, and they are what does the work. Widely available options include avobenzone (Sunbest-AVB) for UV-A, zinc oxide (Sunbest-ZnO) and titanium dioxide (Sunbest-Ti+) as inorganic broad-spectrum filters. In the EU and many other markets you will also see photostable triazines such as bemotrizinol (Sunbest-BMT) and iscotrizinol (Sunbest-HEB), which hold their absorbance under irradiation far better than older filters. Any filter on an approved list has cleared that market's safety review.

5. Get products approved for your market

Approved filter lists differ by country. The EU permits roughly thirty filters under Annex VI of the Cosmetic Products Regulation; the US OTC monograph list is shorter, and bemotrizinol (up to 6%, effective 9 August 2026) is its first new filter since the 1990s; Japan and Australia run their own. A product bought abroad may contain filters not approved where you live, and vice versa.

6. Choose SPF 30 or higher

SPF (Sun Protection Factor) is the ratio of the UV dose needed to redden protected skin to the dose needed on unprotected skin, measured at a standard 2 mg/cm² application. Use SPF 30 as the floor, and SPF 50 for prolonged or intense exposure. Be aware the scale is not linear: SPF 15 absorbs about 93% of UV-B, SPF 30 about 97%, SPF 50 about 98%. Because almost nobody applies the full test dose, the practical gain from a higher number is smaller than it looks; applying enough, and reapplying, matters more than the figure on the bottle.

Sun exposure drives sunburn, photo-ageing and skin cancer risk. Choose a broad-spectrum SPF 30+ that suits your skin and your day, and use it properly. For how the two filter classes compare, see chemical vs physical sunscreens.