Scientists estimate that the human body is made up of around 10 trillion cells in total. Your skin makes up about 16 percent of your body weight, which means you have roughly 1.6 trillion skin cells. Of course, this estimate can vary tremendously according to a person’s size. The important thing is that you have a lot of skin cells. Of those billions of skin cells, between 30,000 and 40,000 of them fall off every hour. Over a 24-hour period, you lose almost a million skin cells.