What Is The Electrical Consumption For My Computer

by on December 18, 2007

Q: How many kilowatts does a computer use per hour?

A: In today’s environmentally conscious world, electricity consumption in general is an important issue. So how much impact does a computer have on a household’s energy consumption? Well, the short answer is anywhere from 1 – 250 watts. Why the range? Well, laptops use electricity at the lower end of the spectrum, anywhere from 15 – 45 watts and when they are asleep, they use anywhere from 1 – 6 watts of electricity. Desktops use anywhere from 60 – 250 watts per hour of activity.

In addition to the electricity usage for the actual computer, there are several other factors that determine your system’s electricity consumption. michaelbluejay.com has an excellent article detailing electricity usage for various computers and components. One of the interesting sections of this site is the More or Less Electricity matrix he has displayed. Here is my rendition of it.

More Energy Less Energy
Ready for Use Standby
Desktop Laptop
Faster Slower
PC Mac
Online Offline

The site also notes that the CPU actually uses very little electricity, it is the monitor and associated devices that get you. For example, you will need to add another 80 watts for a CRT monitor and 35 for an LCD monitor. Add a modem at 7 watts and a router at 4.5 watts, and you can see how your energy consumption adds up quite quickly.

Interestingly, screensavers do absolutely nothing to conserve energy. You will only save energy if you let your computer go to sleep, fading to a black screen.

The website also outlines the specific energy usage for a few machines, so definitely check it out if you are interested.

So how much is it costing you to run your computer? Well, lets say that we are paying $.07 per kilowatt-hour of electricity. We have figured out that we are using 346 watts of electricity per hour for our computer and all associated devices. We can figure out our cost with this equation:
(346 x 40 hours per week)/1000 x $.07 to get our total cost for running our computer in an average week.

Here is the answer: $.969 per week. So it is basically costing us $1 per week to run our computer and all associated devices.

I hope this information helps! Thanks!