General

• The amount of energy an average computer uses varies depending on the type of computer. Desktops can use anywhere between 60 and 220 watts, while laptops use between 15 and 25 watts.
  
  

Considerations

• There are other factors that can increase a computer's power consumptions, such as an LCD screen or a printer. Conversely, computers do not necessarily always run at their peak power consumption level, and thus are not always consuming power at the manufacturer's printed level.
  
  

Turning Off

• Knowing when to turn off a computer is dependent on a few factors. In general, sleep or hibernation mode can save a tremendous amount of power, and turning on a computer does consume a lot of power. However, if you know you won't be using your computer for an extended period of time (over 12 hours), turning it off is a great way to save on power consumption.