How to read your sunscreen label.
SPF measures how much UVB radiation your sunscreen blocks. It is not a measure of time.
A percentage. Not a duration.
SPF measures how much UVB radiation your sunscreen blocks. It is not a measure of time.
At SPF 30, 3% of UVB reaches your skin. At SPF 50, 2% does. At SPF 100, 1% does. Going from SPF 30 to SPF 100 means you are letting in one-third of the UV you were before.
Brandy said it best: “Almost doesn’t count.”
SPF 30 is the floor. For Fitzpatrick V and VI skin or anyone actively managing hyperpigmentation, you can do better and you should.
The minimum UVA tested-against marker.
Broad spectrum means the sunscreen has been tested for both UVA and UVB protection. In the US, a product cannot put “broad spectrum” on the label unless it meets FDA testing standards for both wavelengths.
If your sunscreen does not say broad spectrum, it was only tested against UVB. That means the SPF number on the front tells you nothing about how much UVA protection you are actually getting.
UVA is the wavelength that ages you and darkens PIH. A sunscreen without broad spectrum coverage is an incomplete answer.
In the UK and EU, look for the UVA circle — a circle with “UVA” inside it. That mark means the product meets the EU standard for UVA protection, which requires UVA coverage of at least one-third of the labeled SPF value.
SPF 30 minimum. Broad spectrum, non-negotiable. PA+++ when you can find it. Everything else is marketing.
A more granular UVA rating from Japan and Korea.
The PA system comes from Japanese sunscreen testing standards and is now widely adopted across Asian markets and increasingly by western brands.
PA+ — some UVA protection. PA++ — moderate UVA protection. PA+++ — high UVA protection. PA++++ — the highest available rating.
PA+++ is the minimum for this audience. PA++++ is better for Fitzpatrick V and VI skin or anyone actively managing hyperpigmentation.
If you are comparing a US sunscreen labeled broad spectrum against an Asian sunscreen with a PA rating, broad spectrum does not equal PA++++. The PA system is more granular. When you can find the PA rating, use it.
Forty or eighty minutes. Then it is gone.
Water resistant does not mean waterproof. It does not mean you skip reapplication.
US labeling allows two claims: 40-minute water resistance or 80-minute water resistance. This means the SPF value holds for that duration of direct water exposure under testing conditions. After that window, protection degrades.
Reapply every two hours when outdoors. Reapply immediately after swimming or heavy sweating regardless of the water resistance rating. Those are not suggestions. They are how the SPF on the label actually works in practice.
If you are not going to be in water but you sweat — workouts, outdoor events, humid weather — water resistance still matters. Sweat degrades sunscreen the same way water does.
What to look for, in one paragraph.
SPF 30 minimum. SPF 50 or higher for Fitzpatrick V–VI or if you hyperpigment. Broad spectrum, always, non-negotiable. PA+++ minimum, PA++++ when you can find it. Water resistant if you sweat or go outside. Reapply every two hours.
That is what you are looking for on the label. Everything else is marketing.
Here's how to actually read a sunscreen label. SPF isn't a measure of time, it's a measure of how much UVB gets through — SPF 30 lets in 3%, SPF 50 lets in 2%, and going much higher gains you very little, so SPF 30 is your floor. "Broad spectrum" means it's been tested against UVA too, not just UVB, and UVA is what ages skin and darkens marks, so don't skip it. If you can find a PA rating, common on Japanese and Korean sunscreens, PA+++ is the minimum and PA++++ is better if you're managing hyperpigmentation. "Water resistant" means the SPF holds for 40 or 80 minutes in water, not that it's waterproof — reapply every two hours outdoors regardless, and immediately after swimming or heavy sweating. In one line: SPF 30 or higher, broad spectrum always, PA+++ minimum, reapplied every two hours. Everything else on the bottle is marketing.
Reign in your skin
Almost doesn’t count.
Evaluate your products →Doctor Djeli is an educational resource, not medical advice.