Below is the approximate percentage of UVB rays blocked depending on SPF rating. The difference seems minimal, but a higher SPF helps if you are fair skinned or have a history of skin cancer. Remember, no sunscreen blocks 100% of UV rays.
SPF ratings are significantly decreased if you don’t apply enough. Most people only apply 1/3 of the sunscreen they need. Make sure you use enough and don’t neglect hard to reach and easily forgotten places like your ears, feet, and upper back.
Don’t Forget, The Sun Is Good
20 minutes of daily sunlight (without sunscreen) gives you a healthy does of Vitamin D, which is essential for good health.