Sunscreen in India: SPF, PA+++ and Why Reapplication Matters More Than the Number

SPF measures protection against UVB rays — the ones mainly responsible for sunburn. PA (Protection Grade of UVA), rated in plusses from PA+ to PA++++, measures protection against UVA rays, which penetrate deeper and are the bigger driver of premature ageing and pigmentation. In India’s latitude, with strong year-round UV, both numbers matter; a high SPF with no PA rating is only telling you half the story.

Here’s the part most people get wrong: SPF 50 does not give you roughly twice the protection of SPF 25. SPF 30 blocks about 97% of UVB rays; SPF 50 blocks about 98%. The jump from 15 to 30 matters far more than the jump from 30 to 50. Diminishing returns set in fast, which is why dermatologists generally consider SPF 30–50 with a good PA rating (PA+++ or higher) the practical sweet spot, rather than chasing the highest number on the shelf.

What actually determines real-world protection is less the number and more three habits:

1. Quantity. The SPF number on the bottle is tested at 2mg per square centimetre of skin — roughly a full teaspoon for the face and neck. Most people apply a fraction of that, which quietly cuts an SPF 50 down to an effective SPF in the teens.
2. Reapplication. Sunscreen degrades under UV exposure and rubs off with sweat, humidity and touching your face — all common in Indian conditions. Every 2–3 hours outdoors is the standard guidance, not once in the morning and forgotten.
3. Coverage of missed spots. Ears, back of the neck, hands and the hairline are the most commonly skipped areas, and also common sites for sun damage that shows up years later.

Chemical versus physical (mineral) sunscreen is largely a texture and skin-sensitivity choice rather than a protection-level one — both, applied correctly and reapplied, do the job. The single highest-leverage change most people can make isn’t switching formulas; it’s using enough of what they already have, and putting it on again after lunch.