Beauty & Cosmetics
SPF protection time
Theoretical protection time of an SPF and reapplication reminder.
- Instant
- Free
- Private (processed locally)
- No sign-up
Estimate protection
Pick the SPF rating and your time-to-redden without protection: the tool shows the theoretical protection and reminds reapplication.
Good habits
- Apply generously (≈ 2 mg/cm²)
- Reapply every 2 hours
- Renew after swimming or sweating
- Avoid the sun at peak hours
Example
| Input | Value |
|---|---|
| Rating | SPF 30 |
| Time-to-redden | 10 min |
| Theoretical protection | 5 h 00 |
| Reapplication | Every 2 h |
Informational, not a substitute for dermatological advice. 100% local calculation.
Frequently asked questions
How do I read the result?
Theoretical protection ≈ SPF × time-to-redden. In practice we apply too little cream, so real time is shorter.
How often to reapply?
Every 2 hours, and after each swim, heavy sweating or towel-drying.
Does a high SPF avoid reapplying?
No. No sunscreen protects all day: regular reapplication remains essential.