How Much SPF Do I Really Need?

Many people think that having a higher SPF sunscreen means more coverage, such as a sunscreen with an SPF of 50 providing significantly more coverage than an SPF of 30. These claims aren’t true though, since sunscreen protection increases only slightly for any SPF above a value of 15.

Here’s how sunscreen coverage is calculated:

100 - [1/(x value of SPF given)] x 100=% coverage *

This means that:

SPF 5=100-[1/5]*100= 80% coverage

SPF 15=100-[1/15]*100= 93% coverage

SPF 30=100-[1/30]*100= 97% coverage

SPF 50=100-[1/50]*100=98% coverage

As you can see, the difference between SPF 15 and SPF 30 is only 4%. The difference between SPF 30 and SPF 50 is an even smaller 1%. Though it’s often thought that SPF values increase linearly, the percent coverage after an SPF of 15 doesn’t make the difference in coverage that is often advertised.

The minimal difference between percent coverage of a sunscreen having an SPF of 15 vs. an SPF of 30 or 50 shows that an SPF of 15 is an effective option compared to sunscreens with higher SPF. The protection that SPF 15 sunscreen provides against UVB rays is comparable to the protection that sunscreens with SPF 50 provide.

Sunscreens that have higher SPF values tend to have more chemicals than sunscreen with a lower SPF value, showing that sunscreen with a value of SPF 15 offers a similar level of protection without the same amount of chemicals.

With a difference in sun protection as SPF numbers increase being so small, it seems that higher SPF sunscreen isn’t much better at protecting your skin than a lower SPF of 15. Just because a sunscreen may have a higher SPF, doesn’t necessarily mean that sunscreen will provide much greater coverage than a sunscreen with a lower SPF of 15.

At NŪR, we recommend using a sunscreen with an SPF of 15, with the knowledge that any higher SPF won’t provide much more coverage.

*Kaplan. “Dear Science: What Does Sunscreen SPF Mean, and What Happens If You Mix Them?” The Washington Post, WP Company, 20 June 2016,