Does the SPF of Sunscreen Matter?


Wanna see what happened when they did this kind of test in a clinical research setting, using almost hundred people to compare SPF 50 and SPF 100, applied to each half of their face before going out in the sun for 6 hours. They measured how much sunscreen was used and whether or not they reapplied. And you may be thinking “50 vs 100? does it even matter at that point?” well… here’s what happened.

Many people still burned, and they quantified the severity of the burns (the erythmia score) on a scale of 0 to 2.5.

The OVERALL severity of the burns in the SPF100 areas was less than half the SPF 50.

Here’s the detailed breakdown of how many people burned, on which sides, and how severely.

55% were more sunburned on the SPF 50, compared to 5% on the SPF 100 side.

2 in 5 people had medium severity burns on the SPF 50 side, compared to only 1 in 7 on the SPF 100 side.

And this same difference between the sunscreens was shown even for people who reapplied.

Moral of the story? Higher SPF #’s are good. But if you want to know what exactly that SPF number MEANS, and how much you need to put on, hit that follow because i’ll be covering that next.

Research Studies

SPF 100+ sunscreen is more protective against sunburn than SPF 50+ in actual use: Results of a randomized, double-blind, split-face, natural sunlight exposure clinical trial

Greater efficacy of SPF 100+ sunscreen compared with SPF 50+ in sunburn prevention during 5 consecutive days of sunlight exposure: A randomized, double-blind clinical trial

Sunscreen Surface Area Calculator