Guide
Sunscreen: How Much, How Often, Which Type
If you do one thing from this entire site, make it this. Daily sunscreen does more for pigmentation, texture, and long-term skin health than any serum, and it is the only step with a direct bearing on skin cancer risk. It is also the step most people get wrong, almost always by using too little.
Last reviewed
How much to use
The tested amount is roughly a quarter teaspoon for the face, or two fingers' length squeezed onto your index and middle fingers.
Most people apply between a quarter and a half of that. Since protection scales with quantity, applying half the amount of an SPF 50 does not give you SPF 25 — it gives you considerably less. Under-application is the single most common reason sunscreen disappoints.
What the numbers mean
- SPF measures protection against UVB — the wavelengths mainly responsible for burning.
- Broad spectrum means it also covers UVA, which drives ageing and pigmentation. Look for this explicitly.
- SPF 30 blocks roughly 97% of UVB; SPF 50 roughly 98%. The step from 30 to 50 is small but real, and matters most for pigmentation-prone skin.
- The numbers are not linear. SPF 50 is not twice SPF 25.
Mineral or chemical?
Mineral sunscreens use zinc oxide or titanium dioxide, sitting on the surface and largely reflecting and scattering UV. They suit sensitive and rosacea-prone skin and work immediately on application, but can leave a white cast.
Chemical filters absorb UV and convert it to heat. They tend to be lighter, more cosmetically elegant, and leave no cast, but can sting sensitive eyes and occasionally irritate reactive skin.
Neither is safer or more effective as a category. The best sunscreen is the one you will genuinely apply in the right quantity every day.
Reapplication
- Every two hours in direct sun, and after swimming or heavy sweating.
- Indoors away from windows, a single morning application is generally fine.
- Over makeup, a powder or spray SPF is a practical compromise — imperfect, but better than skipping it.
- Cloud cover does not remove the need. UVA passes through cloud and glass.
Why it matters most alongside actives
Retinoids and exfoliating acids both increase sun sensitivity. Pigmentation treatments are working directly against UV, which is what drives melanin production in the first place.
Using those actives without daily sunscreen is not merely suboptimal — it can leave you worse off than using neither.
Common questions
Do I need sunscreen indoors?
UVA passes through window glass, so if you sit near a window for long periods it is worth applying. Away from windows, the risk is low and a single morning application is plenty.
Is SPF 50 much better than SPF 30?
Slightly — roughly 98% versus 97% of UVB. The bigger variable by far is how much you apply. A well-applied SPF 30 outperforms a thinly applied SPF 50.
Does makeup with SPF count?
Rarely, in practice. You would need to apply far more foundation than anyone does to reach the tested protection. Treat it as a small bonus on top of real sunscreen.
Do darker skin tones need sunscreen?
Yes. More melanin offers some baseline protection but nowhere near enough, and sunscreen is particularly important for pigmentation, which affects deeper skin tones disproportionately.
Skip the guesswork
CURA scans your skin and builds the routine for you — the right steps, in the right order, paced so you do not irritate your way back to the start.