| Percentage of Body Weight | Element | Usage |
| 65% | Oxygen | This element is obviously the most important element in the human body. Oxygen atoms are present in water, which is the compound most common in the body, and other compounds that make up tissues. It is also found in the blood and lungs due to respiration. |
| 18.6% | Carbon | Carbon is found in every organic molecule in the body, as well as the waste product of respiration (carbon dioxide). It is typically ingested in food that is eaten. |
| 9.7% | Hydrogen | Hydrogen is found in all water molecules in the body as well as many other compounds making up the various tissues. |
| 3.2% | Nitrogen | Nitrogen is very common in proteins and organic compounds. It is also present in the lungs due to its abundance in the atmosphere. |
| 1.8% | Calcium | Calcium is a primary component of the skeletal system, including the teeth. It is also found in the nervous system, muscles, and the blood. |
| 1.0% | Phosphorus | This element is common in the bones and teeth, as well as nucleic acids. |
| 0.4% | Potassium | Potassium is found in the muscles, nerves, and certain tissues. |
| 0.2% | Sodium | Sodium is excreted in sweat, but is also found in muscles and nerves. |
| 0.2% | Chlorine | Chlorine is present in the skin and facilitates water absorption by the cells. |
| 0.06% | Magnesium | Magnesium serves as a cofactor for various enzymes in the body. |
| 0.04% | Sulfur | Sulfur is present in many amino acids and proteins. |
| 0.007% | Iron | Iron is found mostly in the blood since it facilitates the transportation of oxygen. |
| 0.0002% | Iodine | Iodine is found in certain hormones in the thyroid gland. |
