A sketch of protected minutes from SPF, unprotected burn time, and UV index.
| Minutes | – |
Use this only as a rough sketch, not medical advice. Minutes ≈ SPF × burn minutes × 3 / UV index. SPF 30, 15 minutes to burn, UV 8 is about 169 minutes in this sketch. Sweat, water, missed spots, and a thin layer cut that. Reapply on the bottle’s schedule anyway. UV index must be greater than zero.
SPF: Rated SPF of the cream.
Burn (min): Minutes to burn with no cream in similar sun.
UV index: UV index from a forecast.
Minutes: Sketch of protected time.
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