How many cells are in your body?

There is no real consensus on the number of cells in the human body. Estimates put the number between ten trillion and one hundred trillion. The number of cells depends on the size of the person: bigger person, more cells. Also, the number of cells in our body keeps changing as old cells die and new ones form.

Cells come in different sizes, and they grow in different densities. If you used their density to estimate the cells in a human body, you’d come to a staggering 724 trillion cells. The mean weight of a cell is 1 nanogram. For an adult man weighing 85 kilograms, simple arithmetic would lead us to conclude that that man has 85 trillion cells.

We have 50 billion fat cells and 2 billion heart muscle cells…Adding up the total number of each kind of cell, the scientists came up with…37.2 trillion cells. This estimate is not including the microbiome - bacteria, fungi and archaea, microorganisms that share our body space.The human body contains over 10 times more microbial cells than human cells.

A cell can die in many ways - through infection, poisoning, overheating or lack of oxygen. An uncontrolled death is messy: the cell swells up, and its contents leak away. This may damage surrounding cells. But there is another way, programmed self-destruction, or apoptosis. Cells often choose to kill themselves. This controlled cell death is crucial for normal human development and good health throughout life. Liver cells last about a year and half. Red blood cells live for 120 days. Skin cells are good for 30 days. White blood cells survive for thirteen days. And it turns out that the great majority of cells in the human body are bacterial cells, and most are beneficial. It is hard to believe that the average adult loses close to 100 million cells every minute. The good news is that the body, through cell division, is replacing those lost 100 million cells every minute.