What does SPF on a sunscreen bottle means and how much SPF is required for daily use?

Doctor's Answer

Photo of Dr Wenus Ho
Dr Wenus Ho

Aesthetic, General Practitioner

SPF or Sun Protection Factor indicates the level of protection against UVB radiation.

Other than the visible light that we can see with our naked eye, the sun transmits UV radiation to the ground as well, which is invisible to us. 95% of these UV rays are UVA rays, with the remaining being UVB rays.

UV radiation causes ageing of the skin and also is a risk factor for the development of skin cancer.

A higher SPF does indicate a better protection against UVB radiation, however the higher you go, the smaller the difference in protection.

  • SPF 15 – Filters out 93% of UVB
  • SPF 30 – Filters out 97% of UVB
  • SPF 50 – Filters out 98% of UVB
  • SPF 100 – Filters out 99% of UVB

Generally, I recommend a SPF of at least 30. Sunscreen needs to be reapplied regularly, especially if outdoor activities are prolonged.

Choosing a sunscreen with good UVA protection is important too and this is indicated by the Protection Grade of UVA (PA rating) and it is indicated by the number of + signs. The more numbers of “+” in a sunscreen, the better it is in protecting against UVA radiation.

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