The amount of sunlight needed for vitamin D production varies by skin tone, latitude, and time of year, and can be estimated using apps like D Minder.

“So, I live at the equator. Half of my heritage is from Sicily, so I have Mediterranean heritage. I tend to get kind of dark when I go in the sun, but I think it depends. ​​Uh there's a great app called D Minder and there's a few others out there that people can find where you can actually calculate how much vitamin D is made based on your skin tone, the latitude, and the place in the world, the time of year, and you can see how much vitamin D you're actually making in your skin.”