How much does the human brain weigh?
An adult human brain weighs about 1.3 to 1.4 kilograms (about 3 pounds). That is roughly 2 percent of body weight, but the brain uses about 20 percent of the body's energy.
Brain size varies from person to person. On average, adult men's brains weigh a little more than women's, mostly because of differences in overall body size. Brain size alone does not determine intelligence. Albert Einstein's brain, for example, weighed about 1.23 kilograms, slightly less than average.
At birth, a baby's brain weighs about 350 to 400 grams, about a quarter of its adult size. It grows very quickly, reaching about 80 percent of adult size by age three and close to full size by early adolescence. Connections between neurons continue to change throughout life.
Compared with animals
The sperm whale has the heaviest brain of any animal, about 8 kilograms, and elephants' brains weigh about 5 kilograms. Humans do not have the largest brains, but we have a large brain relative to our body size and a very large cerebral cortex, the outer layer linked with thinking and language.
Did You Know?
The brain is soft, with a texture often compared to firm tofu or soft butter. Fluid and the skull protect it from bumps.
This answer is general information, not medical advice. For a personal health question, talk to a doctor.