The average human head weighs 10 to 11 pounds. That is about 8 percent of the weight of a human body. The average adult human brain only weighs about 3 pounds, so most of the weight in the head consists of the skull and other fluids.
The human brain weighs about three times more than a chimpanzee's brain and is four and a half times smaller than the brain of an elephant. Albert Einstein had a smaller than average brain that only weighed about 2.7 pounds, but it had more glial cells than average. Humans have over 100 billion brain cells, and some of them survive an entire lifespan.