Most people do not apply enough sunscreen and so the sun protection factor (SPF) labelled on the product is not achieved.
As a guide, adults should aim to apply around:
SPF is a measure of the amount of ultraviolet B radiation (UVB)
protection.
SPFs are rated on a scale of 2 to 50+ with 50+ offering
the strongest level of protection.
The Star Rating measures the amount of ultraviolet A radiation (UVA)
protection.
You should see a star rating of up to 5 stars on UK
sunscreens. The higher the star rating, the better.