How Many Atoms There Are in the Human Body

Atoms in the Body

Scientist analysing molecular model in laboratory

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Have you ever wondered how many atoms are in the human body? Here's the calculation and answer to the question.

Short Answer

There are approximately 7 x 1027 atoms in the average human body. This is the estimate for a 70 kg adult human male. Generally, a smaller person would contain fewer atoms; a larger person would contain more atoms.

Atoms in the Body

On average, 87 percent of the atoms in the body are hydrogen or oxygen. Carbon, hydrogen, nitrogen, and oxygen together account for 99 percent of the atoms in a person. There are 41 chemical elements found in most people. The exact number of atoms of the trace elements varies widely according to age, diet, and environmental factors. Some of these elements are needed for chemical processes in the body, but others (e.g., lead, uranium, radium) have no known function or are toxic contaminants. Low levels of these elements are a natural part of the environment and typically do not cause health problems. In addition to the elements listed in the table, additional trace elements may be found in some individuals.

Reference: Freitas, Robert A., Jr., Nanomedicine, http://www.foresight.org/Nanomedicine/index.html, 2006.

Atomic Composition of a Lean 70-kg Man

Element # of Atoms
hydrogen 4.22 x 10 27
oxygen 1.61 x 10 27
carbon 8.03 x 10 26
nitrogen 3.9 x 10 25
calcium 1.6 x 10 25
phosphorus 9.6 x 10 24
sulfur 2.6 x 10 24
sodium 2.5 x 10 24
potassium 2.2 x 10 24
chlorine 1.6 x 10 24
magnesium 4.7 x 10 23
silicon 3.9 x 10 23
fluorine 8.3 x 10 22
iron 4.5 x 10 22
zinc 2.1 x 10 22
rubidium 2.2 x 10 21
strontium 2.2 x 10 21
bromine 2 x 10 21
aluminum 1 x 10 21
copper 7 x 10 20
lead 3 x 10 20
cadmium 3 x 10 20
boron 2 x 10 20
manganese 1 x 10 20
nickel 1 x 10 20
lithium 1 x 10 20
barium 8 x 10 19
iodine 5 x 10 19
tin 4 x 10 19
gold 2 x 10 19
zirconium 2 x 10 19
cobalt 2 x 10 19
cesium 7 x 10 18
mercury 6 x 10 18
arsenic 6 x 10 18
chromium 6 x 10 18
molybdenum 3 x 10 18
selenium 3 x 10 18
beryllium 3 x 10 18
vanadium 8 x 10 17
uranium 2 x 10 17
radium 8 x 10 10
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Your Citation
Helmenstine, Anne Marie, Ph.D. "How Many Atoms There Are in the Human Body." ThoughtCo, Aug. 26, 2020, thoughtco.com/how-many-atoms-are-in-human-body-603872. Helmenstine, Anne Marie, Ph.D. (2020, August 26). How Many Atoms There Are in the Human Body. Retrieved from https://www.thoughtco.com/how-many-atoms-are-in-human-body-603872 Helmenstine, Anne Marie, Ph.D. "How Many Atoms There Are in the Human Body." ThoughtCo. https://www.thoughtco.com/how-many-atoms-are-in-human-body-603872 (accessed April 21, 2021).