In Sri Lanka, where the UV index regularly hits 11-12, the difference between SPF 30 and SPF 50 is more than just marketing. Let's do the math.
What the SPF number actually means
SPF (Sun Protection Factor) measures how much UVB radiation reaches your skin compared to unprotected skin. SPF 30 blocks ~97% of UVB rays. SPF 50 blocks ~98%. SPF 100 blocks ~99%. At first glance, that 1% difference seems negligible. But percentage of what?
The math that matters
If 100 units of UV are hitting your skin: SPF 30 lets through 3.3 units. SPF 50 lets through 2 units. That means SPF 50 lets through 40% less UV than SPF 30. For daily low-exposure days (commuting, office), SPF 30 is fine. For Sri Lanka's beach days, outdoor work, or hiking, SPF 50+ is the minimum.
Our recommendation for Sri Lanka
Given the UV index and year-round sun exposure here, we recommend SPF 50+ as a baseline for everyone. La Roche-Posay Anthelios SPF 50+ and Bioré UV Aqua Rich SPF 50+ are both excellent options that don't feel heavy in humid weather.
- 1SPF 50+ for daily use in Sri Lanka
- 2Reapply every 2 hours when outdoors
- 3Apply ¼ teaspoon generously to face and neck
- 4Use sunscreen even on cloudy days — 80% of UV passes through cloud
- 5Mineral SPFs (zinc oxide) tend to be kinder to sensitive skin