Sunscreen labels are crowded with numbers, plus signs and claims. Once you know what each one measures, choosing a good one becomes much simpler. This guide explains the main terms and the habits that matter more than any single product.
SPF: protection from UVB
SPF, or sun protection factor, measures protection against UVB, the part of sunlight mainly responsible for sunburn. The American Academy of Dermatology recommends choosing an SPF of 30 or higher. Higher numbers offer more protection, but no sunscreen blocks everything, and the number on the bottle assumes you apply enough of it.
PA ratings: protection from UVA
UVA penetrates deeper into the skin and contributes to tanning, pigmentation and skin ageing. Many sunscreens sold in India, particularly those formulated in Japan and Korea, show a PA rating: PA+, PA++, PA+++ or PA++++. The system was developed in Japan and is based on a test called persistent pigment darkening, which measures how well a product prevents UVA-induced darkening of the skin. More plus signs mean more UVA protection, with PA++++ the highest grade.
“Broad spectrum”
If a label says broad spectrum, the product protects against both UVA and UVB. The AAD recommends choosing a broad-spectrum sunscreen, and a high SPF on its own does not guarantee good UVA protection, so it is worth looking for this phrase or for a high PA rating.
Water resistance
A water-resistant sunscreen keeps working for either 40 or 80 minutes of swimming or sweating, after which it needs to be reapplied. No sunscreen is waterproof.
How much, and how often
Most people use far less sunscreen than the amount used in testing, so they get less protection than the label suggests. The AAD’s guidance is:
- About 1 ounce for the exposed skin of an adult’s body, roughly the amount that would fill a shot glass, and at least a teaspoon for the face.
- Apply about 15 minutes before going outside.
- Reapply every two hours, and straight away after swimming or sweating.
Brown skin, pigmentation and tinted sunscreens
Darker skin has more natural protection against sunburn, but it is more prone to long-lasting pigmentation such as melasma and dark marks after acne. Visible light, not just UV, can worsen these conditions, and most conventional sunscreen filters do little against it.
Tinted sunscreens containing iron oxides can help, because the pigments block some visible light. The AAD notes that a tinted sunscreen with iron oxide may help prevent dark spots. A 2026 review in the Journal of Drugs in Dermatology reached a similar conclusion for people with skin of colour, but also found that almost none of the 37 tinted products it examined listed their iron oxide content online, so it can be hard to compare products.
The short version
- Choose broad spectrum, SPF 30 or more, and ideally PA+++ or PA++++.
- If you are prone to pigmentation, consider a tinted formula with iron oxides.
- Use enough, and reapply. The best sunscreen is the one you will wear every day.
This article is general information, not medical advice. For persistent pigmentation, skin conditions or concerns about specific ingredients, speak to a dermatologist.
Sources
- How to select a sunscreen, American Academy of Dermatology
- How to apply sunscreen, American Academy of Dermatology
- Iron oxides in tinted sunscreens may improve hyperpigmentation protection, Practical Dermatology
- Understanding the PA sunscreen rating system, Paula’s Choice
Lead photo: Mikhail Nilov / Pexels. Facts checked against the sources above in October 2026.
