Asking a Derm: How Much SPF Do You Need In Your Sunscreen?

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Sunscreen application is serious business. Everybody says you should use sunscreen 365 days a year, yet you have so many questions. Is it sunscreen protection or risk? Do we apply sunscreen before or after moisturizer? Or how high should I go with my SPF? Take a seat and relax, you’re about to find out everything you need to know about sun protection factor values and the differences between them.

Does a high SPF protect my skin better?

When the market offers endless possibilities, it’s not easy to decide whether to go for a 30 SPF, 50, or 90. You’ll be surprised to find out there’s no big difference. SPF stands for sun protection factor. An SPF rating dictates how long you can stay in the sun without getting burned. For instance, if it takes you 15 minutes to burn without SPF and you apply sunscreen with 10 SPF, it’ll take ten times longer to burn in the sun, aka 2.5 hours. Basically, it’s a measure of the time it would take your skin to sunburn if you weren’t wearing SPF instead of the time it would take with sunscreen on. 

Hence, higher SPF doesn’t mean better sun protection, just that you’ll stay protected in the sun longer. This means 10 SPF should be applied more frequently than 30 SPF. According to experts, an SPF 15 product blocks about 94% of UVB rays, an SPF 30 one blocks 97% of UVB rays, and an SPF 45 product blocks about 98% of UVB rays. As a matter of fact, the FDA proposed to ban sunscreens labeled with SPF higher than 60 as there’s no scientific evidence to show that they give more protection.

I asked Dr. Meg Sison, Board-Certified Dermatologist how high should the SPF in our sunscreens should be. “Go for sunscreens with an SPF of at least 30. This blocks 97% of UVB rays. Higher numbers of SPFs block slightly more of the sun’s UVB rays, but no sunscreen can block 100% of the sun’s UVB rays. It’s important to use other means of photoprotection as well, like seeking shade when the UV rays are those most intense (10 AM-4 PM), using wide-brimmed hats, UV protective clothing, and UV protective eyewear”, she says. As an aside, SPF refers to the sunscreen’s ability to block UVB rays, but it doesn’t include the UVA ones which, are actually more linked to skin damage. To get great sun protection, pick a sunscreen that provides UVA and UVB protection. 

How much sunscreen should I apply to my face?

“The recommended amount of sunscreen application is 2mg/cm2, which is 1/2 tsp of sunscreen on the face and neck. It is important not to forget to apply on the eyelids, ears, and back of the neck as well because these are the commonly missed spots”, dermatologist Meg Sison said.

There’s a two-finger rule when applying sunscreen for maximum protection. You have to squeeze two strips of sunscreen on both index and middle fingers from the palmar crease to the fingertips. That’s how much sunscreen you should apply to your face. Now you’re good to go.

Who wrote this?
Ana Vasilescu
Ana Vasilescu
Ana is a sociologist and feminist with a shared passion for literature, psychology, and skincare, the combo that made her determined to start Women's Concepts. With over five years of experience in dermatological research, she has now become a certified skincare consultant keen to convince others of the importance of a diligent routine. Her close relationships with dermatologists around the globe, along with years of researching, analyzing studies, and hand-testing products on a daily basis, made Ana one of the best persons you can get advice from.
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