What does SPF stand for?
SPF stands for Sun Protection Factor, this factor tells you how long you can use the product in the sun without burning the UVB radiation.
An average person with light skin burns after about 10 minutes of exposure to the sun. When that person uses a cream with SPF 15, he or she can stay 15 times longer in the sun, so 150 minutes.
In practice this depends not only on the SPF of the sunscreen product, but also on other factors such as the skin type, the amount of sun protection product that is applied and reapplied, the activities that one does etc. That is why it is always important protect yourself against the UV rays and reapply them trough the day. Choose a broad spectrum sun protection product that protects against UVA and UVB rays.
According to their SPF, products are divided into different classes:
Low protection factor: SPF below 15
Moderate protection factor: SPF 15 to 29
High protection factor: SPF 30 to 49
Very high protection factor: SPF 50+
Products with SPF 15 block 93% of UVB radiation
Products with SPF 30 block 96.7% of UVB radiation
Products with SPF 50 block 98% of UVB radiation