How to Calculate Computer Power Supply Usage

With any device that uses electricity, you can normally calculate the amount of power the given device uses by looking at information provided on the unit's power supply box. With computers however, that doesn't always work as well as you might like because the power supply tells you how much maximum power is needed theoretically, not how much you may use generally or on average.

Instructions

1. Use this basic power calculation:
   Amps x Volts = Watts

2. Look at the back of the power supply box to find the amps and volts for laptop computers. For desktop computers, the label may be on either the front or the back of the machine, but it can also be inside the computer box on a label attached to the internal power supply.

3. Multiply the amps times the volts to calculate the watts of power your computer may consume at peak usage.

References

• Saving Electricity: How Much Electricity Do Computers Use?