SPF Guide

SPF - Explained

A few years ago, choosing a good sunscreen meant looking for a high sun protection factor (SPF), rating how well the sunscreen protects against ultraviolet B rays (UVB).

Research soon showed that ultraviolet A rays (UVA) also increase the risk of skin cancer. Whilst UVA rays don't cause sunburn, they penetrate and cause dermal damage.

A High SPF is a false sense of security which can lead to either insufficient sunscreen application or not reapplying as often as you should. If you are going to be outdoors, it is imperative that you reapply your sunscreen every 2 hrs. Sunscreen essentially expires or is no longer effective after that time.

Make sure your SPF is labeled “broad-spectrum” : this will offer protection from both UVA & UVB rays.

Broad-Spectrum Sunscreens:

A sunscreen with broad-spectrum or multi-spectrum protection for both UVB and UVA. Ingredients with broad-spectrum protection include:

  • benzophenones (oxybenzone)
  •  cinnamates (octylmethyl cinnamate & cinoxate)
  •  sulisobenzone
  •  salicylates
  •  avobenzone
  •  ecamsule (Mexoryl SX).
  •  titanium dioxide & zinc oxide


Rates how effective the sunscreen is in preventing sunburn caused by UVB rays. If you'd normally burn in 10 minutes, SPF 15 multiplies that by a factor 15, thus you could go 150 min before burning.


Contrary to what you might think, SPF 30 isn't twice as strong as SPF 15. Whilst SPF 15 filters out 93% of UVB, SPF 30 filters out 97%. Only a slight improvement!

spf guide pdf

Water and sweat resistance.

If you're going to be exercising or in the water, it's worth getting a sunscreen resistant to water and sweat. But understand what this really means. The FDA defines water resistant sunscreens as a SPF level that stays effective after 40 min in the water. These sunscreens are in no way water-proof, so you'll need to reapply.

Sunscreen for skin problems or allergies.

Go for titanium dioxide or zinc oxide instead of chemicals like para-aminobenzoic acid (PABA), dioxybenzone, oxybenzone, or sulisobenzone.

back to top