Sun protection
How to read a UVA rating
PA plus signs, the circled UVA mark and star ratings measure different things on different scales. Here is what each one actually promises.
- Plus signsHow much UVA the product resists
- The circled markUVA at least a third of the labelled SPF
- Star ratingsA ratio, so high stars on low SPF is still low
On this pageWhy UVA needs its own number4
Quick answer
The bottom line
SPF only describes protection from the wavelengths that burn. UVA reaches deeper, drives ageing and pigmentation, and gives you no warning because it does not redden skin. Three labelling systems describe it and none converts cleanly into another: plus signs used in Japan and Korea grade how much UVA exposure the product resists, the circled UVA mark used in Europe certifies that UVA protection is at least a third of the labelled SPF, and star ratings describe the balance between UVA and UVB rather than the absolute amount. The practical rule: if pigmentation or ageing is why you wear sunscreen, look for the circled mark or a high plus-sign rating rather than reaching for a bigger SPF number.
At a glance
Three things worth remembering
- The circled UVA mark used in Europe certifies that UVA protection reaches at least a third of the labelled SPF, so it scales with the number beside it.[1]
Section 01
Why UVA needs its own number
Ultraviolet light reaching skin splits into two useful groups. The shorter wavelengths burn, and SPF measures protection against them. The longer wavelengths penetrate deeper into the skin, contribute to ageing and pigmentation, and pass through window glass.[3][1]
Because they do not redden skin, you get no feedback. Someone can sit by a window every day for years, never burn, and still accumulate damage. That is precisely why a separate label exists.[3]
A formula can reach a high SPF using filters that barely touch UVA. Without a separate requirement, the incentive is to chase the number people shop by.[1]
Section 02
The three systems you will meet
Each grew up in a different market and measures a different quantity. They appear on products sold side by side online, which is where the confusion starts.[2][1]
| Mark | What it measures | What to take from it |
|---|---|---|
| Plus signs after PA | How much UVA exposure the product resists before skin darkens | More plus signs means more UVA protection; widely used in Japan and Korea[2] |
| Circled UVA mark | That UVA protection is at least a third of the labelled SPF | Scales with the SPF beside it, so it is the most useful mark to pair with a number[1] |
| Star rating | The balance between UVA and UVB protection | A ratio, not an amount; five stars on a low SPF is still low protection[1][5] |
| Broad spectrum | That protection extends across a threshold range of wavelengths | A floor, and a low one; it does not scale with SPF[1][3] |
Section 03
Reading a label in practice
Start with the SPF, because every UVA system except the star rating is anchored to it. Then look for a UVA mark that scales: the circled mark, or a high plus-sign rating.[1][2]
If the only UVA claim is the phrase "broad spectrum", you know the product cleared a threshold and nothing more about how well it does at the longer wavelengths.[1][3]
Section 04
The limits of any mark
These marks are certifications from the same testing chain that the recalls called into question. Laboratory work has found products meeting a labelling rule while delivering less UVA protection than a buyer would reasonably assume.[1][5]
A mark is therefore a floor rather than a promise. It is still better than nothing, and choosing a product with a scaling UVA mark stacks the odds better than choosing on SPF alone.[1][4]
Your next step
Turn this into a practical plan
Choose the guide that best matches what you see. Each one starts with what to try, how long to wait and when to get help.