How Much Electricity does a Computer Use?

Dana Hinders
Dana Hinders

Determining the amount of electricity a computer uses can be a somewhat complicated task, since it depends on what type of equipment a person has and what applications he is running. Typically, the amount of electricity a computer uses is between 65 watts and 250 watts. The monitor often needs between 35 watts and 80 watts as well. Most desktop computers have a label that lists how much power they need, but this is generally the theoretical maximum and not an average representation.

Computers tend to use between 65 and 250 watts of power, and monitors tend to use between 35 and 80 watts.
Computers tend to use between 65 and 250 watts of power, and monitors tend to use between 35 and 80 watts.

Desktop computers with faster processors use more electricity than computers with slower ones. LCD monitors only use about half of similarly sized CRT monitors, however. Accessories and peripherals, such as cable modems, routers, or webcams, contribute to a slight increase in how much power a computer uses as well.

An LCD monitor, which uses much less electricity than a CRT monitor.
An LCD monitor, which uses much less electricity than a CRT monitor.

Regardless of what type of computer a person owns, the type of work he does on that computer makes a difference in electrical consumption. Using a computer to edit digital pictures, design a website, or play a video game uses more power than reading email or completing simple word processing tasks. In addition, the amount of electricity a computer uses significantly increases when it is connected to the Internet.

One common misconception is that using a screensaver saves power, but this is not true. Its series of moving images is aimed at protecting the screen from having a static image ingrained into it.

People who are worried about high utility bills will find that a better option is to leave the computer in standby mode when it's not being used. In standby mode, a computer uses approximately 6 watts of electricity and the monitor’s electrical consumption drops to almost nothing. Of course, it's even cheaper to turn the computer completely off when it won't be used for several hours at a time.

Although many people prefer laptops because of their added convenience, it is interesting to note that a laptop computer can also result in a significant energy savings. Most laptops use between 15 watts and 45 watts. Switching to a laptop may be a smart decision for someone who is concerned about how much energy a computer uses.

CRT monitors use more electricity than LCD monitors.
CRT monitors use more electricity than LCD monitors.
Dana Hinders
Dana Hinders

Dana holds a B.A. in journalism and mass communication from the University of Iowa. She has loved being part of the EasyTechJunkie team ever since discovering the joys of freelance writing after her son was born. Dana also hones her writing skills by contributing articles to various blogs, as well as creating sales copy and content for e-courses.

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Discussion Comments


I'm doing an energy project for my science class, and I want to find out how much energy the project took. Thanks!


I am a software consultant. Are there any ways to know how much power is needed for intensive use of such a software?


I was thinking of using a solar panel for my computer since I live in the tropics and work almost 24/7 from the PC. Con you tell me how to choose the right solar panel my computer?


Just let the powerhouse gaming CPU stay on 24/7 and do not sleep or hibernate. It doesn't save much money and you be able to tell. Printers drain a lot of wattage -- not LED monitors!


Post 5 is pretty accurate.

I have a power monitor for the main electrical box by my Alienware and that uses 250 with no SLI idle, 300-350 with dual SLI idle and 350-450 SLI in a game depending on what it is doing.


I have an i7 2600k processor with nvidia 2gb card and a 1500watt power supply and a 2.2kv UPS. I use the computer for about two to four hours on the internet for gaming. How much power will the system use for an hour?


a laptop depends on the graphics card and its processor. I guess that in these times the newest computers that cost around 1000 euros consume about 300 watts, at least!


i want to know how much power does a cpu nd monitor consume in terms of amperage: 6A or 10A. please let me know soon.


I bought a 2500W(5000​W) 12V-240V power inverter so I can attach it to a 12volt 24aH battery (Not a car battery). Can anyone tell me if this will power my laptop power supply? It states 19v 3.42 amps. I just want to know if it will do the job to use a laptop from this inverter.

can anyone help answer this question as I am an electronics virgin!


@anon74056: You are just wrong. a quad SLI system can easily pull over 1500 watts. in fact, if you run quad SLI you will probably need two power supplies to feed it.


Seriously don't underestimate extremely high end gaming PCs. Look up "antec 1200 pulling 2000w" and look at the second result.

my rig: i7 930 @ 4.4ghz; 12Gb 2000mhz ddr3; 240Gb vertex 2; 2x 2tb hitatchi 7200rpm; Gigabyte X58A-UD9; Corsair AX1200w; 2 HD5870 2GBs; 3 Acer V233H monitors in eyefinity.


Even using brand new, highest-end power hogging components for a gaming rig (and let's include 3 or 4 way SLI all on bleeding edge cards, 2-3 large widescreen monitors, raid array(s) with all 10k rpm sata drives, etc), your system power draw will never sit at "up to and over 800 watts."

Yes, you almost certainly need a power supply rated that high (and for the setup in question, possibly higher depending on rails and amps), but even taking such a system and running the most intensive gaming benchmarks 24/7 would not pull anywhere near 800W.

Absolute peak draw on such a system, if you are using fairly inefficient hardware, can get up to right around 800W. Current games (yes, even including crysis), however, don't stress your computer to anywhere near peak load - virtually nothing will, except for benchmarking, stress testing, or folding - none of which are something a normal user is going to do.

A very high-end system will probably sit around 250W idle, 500W typical load. More typical high-end gaming systems today will be around 200W idle, and 400-450W load.

More mainstream (but still fairly expensive) gaming machines will be down to 150W idle, 300-350W load.

A 750W psu can easily handle a souped-up quad sli system, at least in terms of raw power - the issue these days is just making sure there is enough output on the +12v rails.


I borrowed a "Kill A Watt" energy meter from the library, and found that when my computer is in the sleep mode, it uses 105 watts, but when in used it uses 235 watts of power. That means that when my computer is in the "sleep" or hibernate mode, it is the same as leaving a 100 watt light bulb on.

My computer is an el-cheapo desk top model about three years old.


Beware of Gaming computers if you are saving money on electricity. A Gaming computer may use up to and over 800 Watts. An SLi or Crossfire computer with two video cards can suck up wattage.

More hard drives means more motors in your computer running and this will also eat up wattage. If you can consolidate your data from 4x40GB drives to one 200GB drive. However one drive also means that if that drive fails you may lose everything.

SLi is NVidia's Dual Video card system when you get better game proformance. Crossfire is ATI's(AMD's) dual card system. Popular brands like Dell and Gateway will have gaming machines with these dual card setups.

Check your laptop's power cable to see what wattage it is using. For desktops it is harder to find as you may need to open your case to see how many watts your desktop can handle/use. Just because it says the watts there doesn't mean your computer is using all of it.

My laptop can use up to 180watts, but I had to buy something I could game on. My Desktop is rated up to 600 watts, but I am not using all of it.

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