Here's How Often You Should Really Be Reapplying Sunscreen

It's a beautiful, sunny day in the neighborhood and you've decided to spend it walking to the park with your dog. You've got some money for ice cream at the park, your dog's favorite toy, and, of course, you've applied the appropriate amount of sunscreen before leaving the house. You're ready for the sun because your sunscreen will keep you safe from ultraviolet (UV) rays at the park, or will it? Sunscreen is an indispensable sun protection strategy. It shields our skin from harmful UV rays and prevents premature aging and possible skin cancer. 

But sunscreen does not last the whole day. In fact, while you sweat, stay out in the sun, or swim, your sunscreen breaks down and wears off (via The Bright Side). This is why dermatologists and skin experts advise you to reapply broad-spectrum sunscreen with a moderate sun protection factor (SPF) level, which blocks both UVA and UVB rays throughout the day. If you're already taking that step to protect your skin by wearing sunscreen, you might as well do it the right way.

Experts like Dr. Jane Varner, M.D., recommend reapplication of sunscreen at least every two hours (via Sutter Health). If you're swimming, driving, or going to be in direct sunlight for a while, shorten the time between applications to every 80 minutes. Of course, reapplying may seem inconvenient at first, but there are ways to make it easier. Wearing sun-protective clothing, and staying away from the sun as much as you can are sun protection strategies you should add to regular sunscreen application (via Nivea). Except if you've been sweating or by the window, reapplying every four to six hours will do the trick if you're indoors (via the Skin Cancer Foundation). The exception is if you've been in the sun, sweating, or by a window.

Now, you might be asking, "Well, I use sunscreen with SPF 100. Do I still need to reapply?" While many think the number on your sunscreen — the SPF level — means it'll last longer and you don't need to reapply, but that's not what it indicates. The SPF level of your sunscreen denotes how well it can block UV rays (via Colorescience). For instance, SPF 15 blocks 93% of UVB rays, SPF 30 blocks 97%, SPF 50 blocks 98%, and SPF 100 blocks 99%. Sunscreen with a higher SPF level will not last longer than a sunscreen with a lower one; it just has a slightly higher UVB-blocking rate. Reapplying every two hours is essential regardless of the SPF level. 

Before reapplying throughout the day, you need to get your first application right. The best practice is to apply your sunscreen at the end of your skincare routine and before applying makeup (via Paula's Choice). For your body, one ounce of sunscreen, enough to fill a shot glass is enough, Dr. Erum N. Ilyas, M.D., explained via Healthline. 

For your face and neck, Dr. Ilyas also recommended using different items to visualize how much sunscreen you're applying. Like using the two-finger rule, where you apply two streaks of sunscreen on your fingers from the crease between your finger and palm to the fingertip. Others include applying a nickel-sized dollop of sunscreen for the face and neck or using a shot glass, except this time the sunscreen only has to fill the bottom of the glass. Don't forget to apply sunscreen on your ears, behind your ears, your décolletage, and the back of your hands.

Reapplying sunscreen on makeup can be tricky. Sunscreens that come in lotion or cream form are much easier to reapply on the rest of your body or when you have no makeup on. Thankfully, there are techniques you can use when applying sunscreen on top of makeup, and products with SPF are made for this reason. One of them is by using powder sunscreen (via MasterClass). Also called dry sunscreen, powder sunscreen is mineral-based and mimics the feel of setting powder. Most come with a  self-dispensing powder brush like the Colorescience Sunforgettable® Total Protection Brush-On Shield SPF 50 and can be pressed on top of makeup. 

Other options are stick and spray sunscreens like the Tocobo Cotton Soft Sun Stick SPF 50 and the Supergoop PLAY Antioxidant Body Mist SPF 50. Spray sunscreens or sunscreen mists also have the 2-in-1 function of setting your makeup, similar to powder sunscreens. The downside with spray sunscreen however is you can't use them on windy days due to the increased chance of inhalation and difficulty during application (via the American Academy of Dermatology Association). And if you're still team lotion, MasterClass recommends using a makeup sponge to gently dab your sunscreen on top of your makeup. To avoid messing up your makeup, only press into the skin.