This calculator allows you to input the type and number of devices you plan on installing in a new computer system to find out how many watts it will demand from your power supply. It is important to have a power supply that can adequately power all of the devices in your computer. Lack of wattage can lead to unexplained crashes, lockups, and hangs.

Of course, the wattages for each device vary slightly, so the calculator below is only a guideline to show you what you would need at an absolute minimum. Before you spend a lot of money on a gazillion watt power supply, make sure that you really need it!