An adult human has on the order of 30–40 trillion human cells in their body, often quoted as “about 37 trillion cells.”

Quick Scoop

  • Modern estimates put the average adult at roughly 30–40 trillion human cells.
  • Recent detailed analyses suggest about 36 trillion cells for an average adult male and about 28 trillion for an average adult female.
  • Red blood cells make up the majority of these cells, with around 25 trillion red blood cells alone in an adult.
  • If you also count the bacteria living in and on you, the total number of cells associated with your body rises to roughly 70 trillion or more.

In everyday language, it’s fair to say: an adult human is made of tens of trillions of cells , usually rounded to “about 37 trillion.”