The sunscreen is that crucial product every beauty lover vows by. You have apparently heard from everyone the importance of applying the magic lotion whenever you step out of the house and for good reason. Sunscreen not only defends your skin from a tan, but it also prevents the damage caused by disclosure to UV rays.
Early signs of ageing, pigmentation,  are some of the common factors which occur on your face due to sun rays. And all of this can be avoided by the sunscreen lotion as it has “sun protection factor” also known as SPF. 
Till now you have presumably come across a whole range varying from a mere SPF 15 and going up to an SPF 60 to 100. It is very normal to think a higher SPF would mean better results, but it is not compulsory always. 
SPF is an evidence of how much sun exposure you get the moment you step outside. This means, the larger the appearance of the sun’s rays on the skin, the higher the SPF. SPF 15 would protect you against 93% of the UVB rays, SPF 30 against 97 %, SPF 50 against approximately 98%.
In short, the more your body will be exposed to the sun, the higher SPF content you need.

The SPF is only powerful if you apply your sunscreen right. Applying a small amount isn’t going to be defending you from the sun for a long time. Keep in mind that you need about half a teaspoon of sunscreen for your face, while a good shot-glass size of sunscreen will do the treat for your body.