How Much Energy the Brain Uses

For an adult at rest, the brain’s total metabolic rate is often estimated at about 20 watts. This is metabolic power—the rate at which tissue uses energy from nutrients—not electricity that can be drawn from the brain. A light-bulb comparison refers only to the order of power: LED bulbs vary in wattage and brightness. The brain continually supports neural signaling and information processing, but complex brains and computers cannot be compared by a single wattage figure.