How Much Does the Human Adult Brain Weigh?

A human adult's brain weighs about 3 pounds (1.5 kg). Scientists believe that the modern human adult's brain is about 10% smaller than it was 10,000 years ago, which is thought to be due to the introduction of agriculture and less of a need to be hunter-gatherers. A human adult's brain is about three times as large in relation to the rest of the body when compared with the brains of other similarly sized mammals. It also uses up a large amount of energy, requiring about 20% of the body’s energy supply even though the brain is just 2% of the body’s mass.

More about the brain :

The brain makes up 80% of the contents of the human skull. The rest is equal amounts of blood and brain fluid.

Humans have been found to be unable to use the parts of their brains responsible for multitasking until after the age of 17.

Neurons, the cells responsible for transmitting information from the brain, comprise just 10% of the brain. Most of the brain's mass is glial cells, which hold neurons together.