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Calculate sunscreen needed from body area, SPF and time outdoors — see amount, reapplication and protection.
Calculate sunscreen needed from body area, SPF and time outdoors — see amount, reapplication and protection.
Enter values above and click Calculate — results will appear here with the formula explained.
Sunscreen amount is 2mg per sq cm: face 5ml (teaspoon), face+arms 15ml, full body 35ml (shot glass). Reapply every 2 hours, after swimming/sweating.
SPF 30 blocks 97%, 50 blocks 98% — higher SPF not double. Proper amount matters more than high SPF.
For YMYL skin health, daily SPF 30+ on face prevents aging and cancer, even cloudy.
Calculate sunscreen needed from body area, SPF and time outdoors — see amount, reapplication and protection. Formula: Amount: face 5ml, face+arms 15ml, full 35ml. Example: Face+arms 15ml, SPF 50, 4 hours: need 15ml *2 applications =30ml total, 98% block.
Sunscreen amount is 2mg per sq cm: face 5ml (teaspoon), face+arms 15ml, full body 35ml (shot glass). Reapply every 2 hours, after swimming/sweating.
SPF 30 blocks 97%, 50 blocks 98% — higher SPF not double. Proper amount matters more than high SPF.
For YMYL skin health, daily SPF 30+ on face prevents aging and cancer, even cloudy.
Face+arms 15ml, SPF 50, 4 hours: need 15ml *2 applications =30ml total, 98% block.
Formulas are standard public references (see our methodology). External standards are cited in the text where they apply.
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