How to Use the Sunscreen Dosage Calculator
Most people apply far less sunscreen than needed, which significantly reduces protection. By selecting your skin type, activity environment, and SPF, this calculator shows the correct amount to apply and when to reapply.
The FDA-recommended application amount is 2mg per cm². Studies show that most people apply only 25–50% of this amount, meaning their actual protection is much lower than the labeled SPF. Applying the full recommended amount is especially important for extended outdoor exposure.
Frequently Asked Questions
No. SPF measures blocking strength, not duration. Even SPF 100 products need reapplication every 2 hours. Higher SPF does provide more protection per application, but the timing of reapplication stays the same.
Mineral sunscreens with zinc oxide (ZnO) or titanium dioxide (TiO2) are less irritating and sit on top of the skin. Choose fragrance-free and alcohol-free formulas for minimal irritation.
Yes. Clouds block only about 20% of UV-A rays. Skin damage can still occur on overcast days. Use at least SPF 30 year-round for daily skin protection.