Sun Protection Factor – The Higher The Better?

Do you know the meaning of the SPF number on your bottle of sunblock? Is it true that a bottle of SPF 100 sunblock provides greater protection than a bottle of SPF 30 sunblock? Is the SPF all that you look for when you purchase a bottle of sunblock? This post seeks to help you make better decisions when you purchase your next bottle of sunblock.


The sun protection factor (SPF) measures the amount of protection provided by the sunblock to block UVB rays. UVB rays are the main cause of getting sunburns. So what exactly do the numbers mean?

SPF 15 blocks about 93% of UVB rays
SPF 30 blocks about 97% of UVB rays
SPF 50 blocks about 98% of UVB rays
SPF 100 blocks about 99% of UVB rays

From the above, you can see that an SPF 30 sunblock isn’t twice as effective as an SPF 15 sunblock. There is only a marginal increase in effectiveness in blocking UVB rays as the SPF increases. In fact, no sunblock offers 100% UVB protection. Most importantly, using a sunblock with a higher SPF value does not mean that you can apply the sunblock less frequently! Regardless of SPF value, the sunblock would probably be gone after a few hours. The National Skin Centre (Singapore) recommends a water-resistant sunblock to be reapplied every 2 hours (1 hour if you have been swimming). This means that sunblock that is not water-resistant should be applied much more frequently as your perspiration would have caused the sunblock to wear off faster.

Protection Grade of UVA (PA)

Having mentioned so much about UVB, you may be wondering if there is a UVA, and whether it is important at all. If you are concerned about your looks, UVA is VERY important! UVA accelerates the aging of your skin! On top of that, UVA has been found to result in long-term skin damage and just like UVB, can cause skin cancer.

Most sunblock now offers both UVA and UVB protection. UVA protection may be indicated by phrases such as “broad spectrum” and “multi spectrum”. Many also use PA to indicate UVA protection, with PA+++ offering more UVA protection than PA++.

Now that you know more about UVA and UVB protection, be sure to get the bottle of sunblock that provides you with the level of protection that you are comfortable with, and reapply it frequently!