Skin Health Skin Care & Cleansing Products The Proper Way to Apply Sunscreen By Heather L. Brannon, MD Heather L. Brannon, MD, is a family practice physician in Mauldin, South Carolina. She has been in practice for over 20 years. Learn about our editorial process Heather L. Brannon, MD Medically reviewed by Medically reviewed by Casey Gallagher, MD on July 19, 2020 Casey Gallagher, MD, is board-certified in dermatology and works as a practicing dermatologist and clinical professor. Learn about our Medical Review Board Casey Gallagher, MD on July 19, 2020 Print We're constantly being told how important it is to wear sunscreen, but rarely are we told how to wear it. If you've ever wondered if you're using sunscreen the right way, you aren't alone. Maybe you've wound up with a nasty sunburn even though you took time to apply SPF. Read on for everything you need to know about proper sunscreen application. OJO_Images / Getty Images The Difference Between Sunblock and Sunscreen Although sunblock and sunscreen do the same things, they work a bit differently. Sunblock blocks UV rays and starts working the moment you put it on. Sunscreen, however, works by absorbing into the skin. It needs to be applied 20 to 30 minutes before sun exposure to give it ample time to sink in. The one thing that doesn't vary between sunblock and sunscreen is SPF. A sunblock and a sunscreen that are both SPF 30 provide the same level of protection. Between the two, there is no "better" product. The best sunscreen or sunblock is the one you enjoy and know how to use. How to Apply Sunscreen Sunblock, as previously mentioned, works immediately, but sunscreen needs at least 20 to 30 minutes to absorb into the skin before sun exposure. Both products are applied the same way. The only difference is timing. Shake the bottle well before you squeeze any sunscreen out. This mixes up all the particles and distributes them evenly in the container.An adult should use about 35 milliliters or 1 ounce of sunscreen to cover their entire body, which is the same amount that would fit into a shot glass. It's also about the same as an adult handful. Remember: most people don't apply enough sunscreen, so it's okay to use more than you think you should.Cover all of your skin that will be exposed to the sun. This includes often neglected areas like your back, ears, behind your knees and your legs.Continue to reapply throughout the day. If you've been in the sun for 30 minutes, you might want to reapply more sunscreen to get any places you might have missed. Definitely reapply 1 ounce of sunscreen at least 2 hours, even if you haven't been sweating or swimming.Always reapply 1 ounce of sunscreen after swimming, sweating or toweling off. Get the Most out of Sunscreen Sunscreen application isn't a once and done deal, and just because you're wearing sunscreen doesn't mean you can't get burned. Get the maximum sun protection possible by following these tips: Always reapply. Reapplication is just as important as the first application. Set an alarm to help you remember.It's okay to apply more sunscreen than you should. Better to apply too much than not enough.Wearing sunscreen doesn't mean you're immune to sunburn. You're more likely to get a sunburn when the sun's ray are at their most intense, during 10 a.m. and 4 p.m.Watch your SPF. The SPF number tells you how long you can stay in the sun without getting burned. For example, if it normally takes you 15 minutes to burn when you aren't wearing sunscreen, applying an SPF 10 means it will take you 10 times longer, or 2.5 hours, to burn.Insect repellents can reduce a sunscreen's SPF by up to 1/3. If you're using a sunscreen and insect repellent together, use a higher SPF and reapply more often. Was this page helpful? Thanks for your feedback! Sign up for our Health Tip of the Day newsletter, and receive daily tips that will help you live your healthiest life. Sign Up You're in! Thank you, {{form.email}}, for signing up. There was an error. Please try again. What are your concerns? Other Inaccurate Hard to Understand Submit