What percentage of the human body is water?
Water makes up about 60 percent of an adult human body. Babies are about 75 percent water, and the share falls with age and with more body fat.
Water is found inside cells, in the fluid between cells and in blood plasma. The brain and heart are about 73 percent water, the lungs about 83 percent and even bones about 31 percent, according to the US Geological Survey. Fat tissue holds less water than muscle, so the percentage differs from person to person.
Adult men average around 60 percent water and adult women around 55 percent, mainly because women tend to have a higher share of body fat. Newborn babies are the wettest humans, at about 75 percent.
What all that water does
Water carries nutrients and oxygen to cells, removes waste through urine, cushions joints, protects the spinal cord and helps control body temperature through sweating. Because we lose water constantly through breath, sweat and urine, it has to be replaced every day from drinks and food. Losing just a few percent of body water can cause headaches and tiredness.
Did You Know?
The amount of water a person needs depends on climate, activity and size. Food provides a share of daily water, especially fruit and vegetables, and thirst is usually a reliable guide for healthy adults.
This answer is general information, not medical advice. For a personal health question, talk to a doctor.