How it Works
Natural Burn Time * SPF Factor.
What is Sunscreen Reapplication Timer?
Burn Time * SPF.
Step-by-Step Guide
1. Skin Type
Est. burn time.
2. SPF
Product strength.
3. Limit
Safe duration.
Example
Input: 10 min burn, SPF 30
Result: 300 Mins
FAQ
Does SPF 50 last longer?
Marginally. It blocks more rays, but duration is similar.
Swimming?
Water resistant ≠ Waterproof. Reapply immediately.
Cloudy days?
UV rays penetrate clouds; wear SPF.
Expiry?
Sunscreen loses potency after 3 years.
Quantity?
Shot glass full for the body.
Conclusion
Dermatologists recommend reapplying every 2 hours regardless of math, especially if sweating or swimming. SPF is not linear.