SPF 30
When you need more protection than your standard SPF 15, then opt for a sunscreen of SPF 30. No sunscreen would be complete without its SPF rating. The Sun Protect Factor is important in stating how long you can stay under the sun before your skin starts to burn from exposure to ultraviolet rays.
What is the difference between using a sunscreen with a rating of 30 compared to 15? When you use the SPF formula that helps to calculate how many minutes you can stay in the sun without burning, the numbers work out this way...
If your skin tends to burn after being in the sun unprotected for 10 minutes, using a sun care product with SPF 30 means you can stay out in the sun 30 times longer before experiencing a sunburn. So 10 minutes x 30 = 300 minutes, which means you can stay out in the sun for about 300 minutes (approximately five hours) before getting burned.
But a word of caution... the only way to make any sunscreen work effectively throughout the day is to reapply it every two hours. That means just one application won't necessarily keep your skin safe from UV rays if you plan on being out for five hours straight. Sweat and excessive rubbing/wiping can easily remove your sunscreen, leaving your skin unprotected. Reapplication is always the key to making sunscreen work for you.
Most people feel safer using SPF 30 because of the extra protection but it's up to you to decide which SPF rating will suit your skin's needs. If you know that your skin burns easily or that it doesn't take very long for it to get sunburned, you may want to look into using a sunscreen with an SPF rating of 30 to cover all your bases. Also make sure you choose a product that is labeled as a broad spectrum sunscreen that will effectively fight against both UVA and UVB rays.