Dermatologist reveals exactly how much sunscreen you need

You won’t burn after reading.

With a startling number of adults confessing to never wearing sunscreen, an NYC-based board-certified dermatologist is revealing exactly how much you need to prevent sun damage.

“Two finger lengths should cover your face, your neck and the ears for most people — it’s a pretty good rule of thumb,” Dr. Whitney Bowe explained in a TikTok that’s drawn more than 18,100 views this month.

“I tend to err on the side of caution, so I use two finger lengths just for my face, and then I go in with extra sunscreen for my ears and my neck,” she added.

Bowe filmed her 35-second clip while applying ISDIN Photo Eryfotona Actinica SPF 50+.

She noted that these mineral sunscreens — which rely on zinc oxide or titanium dioxide to reflect ultraviolet light from the sun — need to be thoroughly rubbed in to avoid leaving a white cast.

The two-finger sunscreen rule is not new. It dates back at least two decades, and it has come under fire for its one-size-fits-all approach.

Dr. Caren Campbell, a board-certified San Francisco dermatologist, says to go for an ounce or the size of a shot glass.

She said it’s imperative to cover your ears, the tops of your feet, your head, scalp and neck with sunscreen.

“Some of the most aggressive skin cancers occur on your temples, ears and lips oftentimes because those are areas of the body that stick out and get more sun, but also because we forget to lather them in sunscreen,” Campbell told CNET this month.

The advice comes as 33% of American adults polled this month by Yahoo News/YouGov admit they never wear sunscreen.

It’s one of the worst summer mistakes you can make, along with peeling your sunburn and drinking in the sun.

The American Academy of Dermatology recommends an SPF of at least 30, which blocks 97% of the sun’s UVB rays.

Sunscreen should be reapplied every two hours or right after sweating, being in the water or toweling off. Reapply water-resistant sunscreen every 40 to 80 minutes.