SPF 30 vs 50 vs 100: Does a Higher Number Really Protect You More?
The real percentages behind SPF 30, 50 and 100 are closer than the marketing suggests—and a big number can quietly encourage riskier behavior.
Dermatologists cited by PBS NewsHour note that SPF 30 blocks about 97% of UVB, SPF 50 about 98%, and SPF 100 about 99%; the FDA has proposed capping labeled SPF claims at 60 because higher numbers offer diminishing returns and can encourage riskier sun behavior.
Dermatologists interviewed by PBS NewsHour emphasize that the leap from SPF 30 to SPF 100 buys only a couple more percentage points of UVB blocking, and warn that very high numbers can lull people into staying out longer or skipping reapplication—undermining the extra protection on paper.
Questions we get a lot
How much more does SPF 100 block than SPF 30?
As dermatologists told PBS NewsHour, SPF 30 blocks about 97% of UVB, SPF 50 about 98%, and SPF 100 about 99%. So going from SPF 30 to SPF 100 adds only about two percentage points of UVB blocking. The difference is far smaller than the numbers suggest.
Why did the FDA propose capping SPF at 60?
According to PBS NewsHour, the FDA has proposed capping labeled SPF claims at 60 because higher numbers deliver diminishing returns in UVB protection. There is also concern that big numbers encourage riskier sun behavior, like staying out longer or skipping reapplication. The cap aims to keep labels meaningful.
What SPF should I actually use?
Dermatologists cited by PBS NewsHour generally recommend at least SPF 30 broad-spectrum for daily use. Beyond that, application matters more than the label number—most people apply too little, which lowers real-world SPF. Reapplying regularly and seeking shade does more than chasing the highest SPF on the shelf.
r/SkincareAddiction: 'Is buying SPF 100 actually worth it, or am I just paying more for basically the same protection as SPF 50?'