Free tool

Sunscreen guide and calculator

Work out how much sunscreen to apply, how often to reapply and how long your bottle will last, using the American Academy of Dermatology's guidance.

Where are you applying it?

Mineral vs chemical

Mineral sunscreens use zinc oxide and/or titanium dioxide as their active ingredients. In its proposed order for over-the-counter sunscreens, the FDA said it had enough safety data to propose both as generally recognized as safe and effective (GRASE).

Chemical sunscreens use other UV filters, such as avobenzone or oxybenzone. The FDA has asked for more safety data on these, but says this is not a conclusion that they are unsafe, and it has not required any sunscreen to be pulled from the market.

"Reef safe"

"Reef safe" is not a defined or regulated term in the US, so brands can use it freely. Check the active ingredient list instead. Since January 1, 2021, Hawaii has banned selling or distributing sunscreen that contains oxybenzone or octinoxate without a prescription, to help protect coral reefs and marine life.

Questions

How much sunscreen should I put on my face?

At least 1 teaspoon, about enough to cover the length of your index and middle fingers, according to the American Academy of Dermatology.

How much sunscreen do I need for my body?

Most adults need at least 1 ounce, about a shot glass full, to cover skin not covered by clothing. Larger bodies may need more.

How often should I reapply sunscreen?

At least every 2 hours, and right away after swimming or sweating. Water-resistant labels say whether protection lasts 40 or 80 minutes in water.

What is the difference between mineral and chemical sunscreen?

Mineral sunscreens use zinc oxide and/or titanium dioxide as active ingredients. Chemical sunscreens use other UV filters such as avobenzone or oxybenzone.

Is "reef safe" sunscreen regulated?

No. "Reef safe" is not a defined or regulated term in the US, so check the active ingredients. Hawaii has banned selling sunscreen with oxybenzone or octinoxate without a prescription since January 1, 2021.

Sources

  1. How to apply sunscreen (American Academy of Dermatology)
  2. Skin care tips dermatologists use (American Academy of Dermatology)
  3. When to replace makeup and sunscreen (American Academy of Dermatology)
  4. Sunscreen: How to Help Protect Your Skin from the Sun (FDA)
  5. Questions and Answers: FDA posts deemed final order and proposed order for over-the-counter sunscreen (FDA)
  6. 21 CFR 201.327 Over-the-counter sunscreen drug products; required labeling (eCFR), paragraph (i)(4)(iii)
  7. Skincare Chemicals and Coral Reefs (NOAA National Ocean Service)
  8. Why are some Sunscreens Labelled as "Reef-Safe"? (McGill University Office for Science and Society)
  9. Hawaii SB2571 (2018), Act 104, bill text (LegiScan)

This tool is general information, not medical advice. Patch-test new products and ask a dermatologist about skin conditions.