How Many Kilowatts Does a Computer Use?

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The central processing unit (CPU) in the average desktop computer uses between .06 to .3 kilowatts per hour (kWh). A laptop computer uses approximately 72 kWh.

A desktop computer includes two primary powered components: the central processing unit (CPU) and the monitor. The CPU uses around .06 kWh until the processor is under load. At 100 percent load, the CPU may use .09 kWh. In hibernation, the CPU may use between .003 and .035 kWh. A cathode ray tube (CRT) monitor adds another .08 kWh, while a flat-screen monitor adds around .035 kWh. A laptop computer includes its CPU and monitor in a single unit and can use 72 kWh.

The power used by either a desktop or laptop computer will depend on a number of factors:

  • Age of computer
  • Type of video card
  • Use

For example, a computer with a high-end video card for gaming or other graphics-heavy applications will use more kWh than a basic machine used primarily for word processing.