Complete Guide on How to Calculate your PC’s Energy Consumption

how to find out how much wattage your computer is using

As PCs and other computers become more powerful and can handle more complex tasks, their energy use increases as well. In fact, the power consumption of an average PC increases with the complexity of the tasks as well: playing video games and rendering photos and videos are some of the more complex tasks your computer can do, and they draw a lot of power and take hours to finish. This handy guide will show you how to calculate or measure how much power your computer uses. 

PC Power Consumption

Needless to say, your PC power Consumption is higher than you may expect. High-definition video, playing video games, and using your computer for all sorts of different tasks have their toll on the computer chip – and your electricity bill. Having a powerful video card can also significantly increase your PC’s power use – consider that these cards are often used to mine crypto. 

If you’ve recently bought a new PC and have used it for prolonged periods of time, you may have noticed that your power usage went up and that your power bill is higher than usual. The odds are that your PC consumes the extra energy. And the more powerful and expensive your computer is, the more power meters will count every day. 

For this reason, you may want to learn more about your PC power consumption and how much power your computer actually draws from the power supply. Needless to say, some people simply need the computer to talk with their friends and work – in this case, it pays off to pay the few bucks on top of your power bill – especially if it is through the computer that you make manifold that amount. With no further ado, let’s go and see how you can use software and hardware solution to see how much power your PC uses. 


When it comes to software solutions, it is useful to know that they are not an almighty source of information. They can give you a rough estimate of how much power your computer has consumed in a certain, usually short, period of time. If you want a more detailed overview of your power consumption, you may want to skip to the hardware solutions right away. However, as not many people want to go to the hardware store for a simple meter and Amazon may take a few days to deliver, let’s consider the most popular software to see what your PC power consumption is: 

  • Local Cooling, 
  • Open Hardware Monitor, 
  • OuterVision, 
  • Power Meter, and 
  • Power Supply Calculator.

Local Cooling 

Local Cooling can help you estimate just how much juice your computer is using. You can download and install the app, click the settings buttons and then go to the power tab. You should be able to see the power usage of each individual component, such as the CPU and GPU. 

Open Hardware Monitor 

Open Hardware Monitor is a lightweight application. This app goes about on its own to collect the data about your PC. Once installed, you will be able to see energy consumption, temperature sensor reading (on the cooling system), as well as your graphics card power consumption, and other computer components. 


OuterVision is a powerful tool that you can use to get detailed specs on your PC’s power consumption. The solution is detailed enough to provide you with power usage (in real-time) of every single component of your PC. You may need to enter the details of some of the components by yourself. 

Power Supply Calculator 

Power Supply Calculator is an online tool that can help you estimate your PC’s power consumption. Different from other solutions on our list, the web platform allows you to manually enter your PC’s components, and it calculates the power use of your PC based on what you’ve entered. 

This is a tool that helps estimate power consumed and may not be the best solution for real-time energy use. It is more than helpful, however, in helping you estimate the power consumption if you plan to build your own PC. In this case, you can estimate your power budget as well and see what kind of machine you can build. 


When it comes to hardware solutions, some of them are already built into your computer. This is how software solutions know your computer’s power consumption. However, with these solutions, it is difficult to see how much power the (liquid) cooling kits draw and how much energy is delivered to the motherboard. 

This is where hardware solutions come into play. If you would like to invest and know how much power your computer uses, it is best to purchase a power meter. Solid and reliable, a good power meter will easily measure the power your computer consumes. As it plugs behind the computer in the wall socket, it will also be able to account for the losses that happen as the power supply converts the alternating current (AC) into direct current (DC) that your computer needs to power itself. 

Most meters are of good production and will last you for years. They have a low margin of error of only 5%, so they are a much better option for measuring the total power consumption of your PC components than software solutions are. In addition to this, these meters can also account for small differences in power consumption, such as when fan speeds change. 

kWh Calculation

All these solutions to understanding how much power your PC uses have their own limits. First of all, software solutions cannot measure any losses that happen as electricity travels through electronic devices. Secondly, they also cannot measure (at least reliably) the power consumption of various devices you may connect to your computer – do not forget that every time you connect your phone to the computer, it starts drawing power from it to recharge its own battery. 

In addition to these known issues, software solutions cannot track vampire energy use when your computer is on standby mode. Likewise, they have difficulties tracking minor changes in power consumption, such as blinking LEDs and fan speed changes. For these reasons, it may be best to invest in a power meter. Most of them cost around $20 and can measure all of those minor changes. 

Once you have the metering, it is time to do the kWh calculation. Try to understand how many hours in an average day you use your computer. This number can be anywhere from 1 to 24, depending on what you do with your computer. Then, simply multiply that number by 30.5 (for an average month), and you will get how many hours you use the computer in an average month. 

Multiply that by average power consumption, and you will get how much power your computer uses every month. Additionally, multiplying with the cost of electricity in your area will yield the total cost. Let’s take a look at an example: 

Your computer uses 200W per hour or 0.2 kWh per hour. You use it for an average of 4 hours a day and 10 hours on the weekends. This yields an average daily use of about 6 hours a day. Let’s do the math: 

0.2 kWh X 6 hours a day X 30.5 days a month = 36.6 kWh per month

If you live in an area where electricity costs $0.20 per kWh, at the end of the month, you will pay: 

36.6 kWh X $0.20 per kWh = $7.22 per month 

Please bear in mind that this estimate is for a regular computer running simple programs, such as a word processor. Playing video games and rendering images or videos will significantly increase power consumption. The same can be said for any attached peripherals, such as speakers, routers, additional displays, and any other hardware. 

PC Running Costs

Your PC running costs are not too high, at least in an average setting. However, if you use your PC professionally, for longer periods of time, or have a high consumption set up, this will draw more power from the wall outlet and will increase how much power your PC uses. The same goes for setups with CPU and GPU overclocking, as this significantly increases power use. Let’s consider factors that affect your PC energy use: 

Factors Affecting your PC Energy Usage

Although PCs are made to use very little energy for every task they do, it is important to understand that the tasks computers can do nowadays are very complex and take a lot of power. As it is impossible to know the exact power requirements of any PC setup, as there are simply too many variables, it is best to purchase a watt meter and take a general notion of all the factors affecting your PC energy usage

Computer Components

Computer components are the most important part to consider when trying to understand your PC’s power consumption. A watt meter can give you a pretty good idea of the kind of expenditure your PC or laptop is making. Although there are great ways to save here, you should understand that purchasing components that draw less power usually means less computing power and an overall slower PC as well. Here are some common components that you should check the power usage of before building your own setup: 

  • The motherboard – the highway that information travels through, the motherboard is an essential part of any setup. This is where all other components connect to, 
  • RAM memory – Random Access Memory chips are becoming smaller, with a higher capacity and speed and improved energy efficiency. Extra high-performance components draw a lot of power, 
  • GPU – Graphics Processing Unit can draw the most power in any setup. The graphics card is power hungry, as they render a lot of graphic details and imagery. This is especially true for GPUs used in architecture, gaming, and video rendering. 
  • CPU – Central Processing Unit is the brain of every computer. Clock speeds may be exceeded when the CPU is overclocked and may cause higher energy use. 
  • Optical Drive – whenever in use, it can draw around 20 Watts of power. Bear in mind that Blue Ray disks may even increase this power consumption, as there is more information to read from them, and the drive may not make a single brake. 
  • HDD – Hard Disk Drive – this is the memory where all your information, including media and work-related files, is stored in. To reduce energy use and increase your PC’s speed, purchase a single SSD – Solid State Drive. Although more expensive, they offer much better performance
  • PCI cards – offering specialized services and capabilities, they draw the power whenever in use. 
  • USB Devices – USB ports draw power when in use. In addition to this, any device that has a battery and is connected to your PC will recharge that battery for as long as it is connected to the computer. 
  • LED systems, temperature sensors, and other PC hardware can also increase how much power your PC build is using. Although there are other devices besides these, they do not contribute to energy use as much. 

PC Usage

One more of many factors that affect energy use and how many watts your PC draws is the usage. A user spends around 4 hours a day on their PC. On the other hand, professional users and users of gaming computers may spend even more time on their machines and significantly increase their power use. Advanced users, such as those using professional rendering software in video editing, photography, imaging, and architecture, may use even more power. 

Just consider that rendering a single, high-quality video can take an entire night. During this time, both your CPU and GPU will work at their maximum level and will significantly contribute to your electric bill. Video cards, if there is one, also draw a lot of power. 

Online Activity

Although online activity per se does not draw a lot of power, playing online multiplayer games and having many tabs open at the same time can significantly increase your power consumption. In addition to all the computer components, clock speed, and CPU utilization, the router enabling all this online traffic and any ports it may be connected to (unless you’re using WiFi) will draw power. Wireless connections (WLAN) also draw power, as the transmitter and receiver have to do the work of the wires. 

Type of Computer

Finally, the type of computer you use has a huge say in how much power you will draw with each passing second. Let’s consider some common types of computers and their power use: 

  • Supercomputers – supercomputers and supercomputer clusters are huge users of energy and are generally used by Universities and banks to digest a lot of data, much more than an average user needs, 
  • Office Computers – a type of a PC, this computer does not draw a lot of power. It is mostly intended for word processing and simpler tasks. 
  • Personal (Home) Computer – or a PC, this type of computer draws more power than an office computer but less than supercomputers, 
  • Laptop – the winner in any care, a laptop uses the least amount of energy. Most laptops draw as little as 45 Watts of energy, almost five times less than an average PC. They may not always be suited for gaming and complex tasks, as they can overheat, but they are the best solution for most users due to their portability. 
  • Mining Rigs – specialized computers that are used to mine blockchain currencies. These computers draw a lot of power, more than several PCs at once. Some innovative people from the US even use farms of these rigs to heat their homes during winter while mining crypto. 

PC C02 Emission

An average PC setup does not have a significant CO2 impact, at least not in comparison to some other electronic devices and appliances. However, if you would like to even further reduce how many watts come from dirty energy sources and your carbon footprint, you may want to consider: 

  • Purchasing a green energy plan
  • Purchasing an energy-efficient PC or laptop, 
  • Switching to a laptop, as they use up to 80% less energy than a PC, and 
  • Installing solar panels – even one is enough to completely offset your PC CO2 emissions. 

You may also want to consider some tips for saving energy: 

Tips for Saving Energy

Although PCs do not use a lot of power, they are still complex machines that work long hours and can increase your power consumption significantly by the end of the month. An average PC, if left on for a full month, will use up as much as 146 kWh of energy – a significant addition to your energy bill. For this reason, here are ways to save energy with your PC: 

Turn Off Your PC

Turn off your PC whenever not in use. You can leave it on whenever making a short break, such as a coffee break or when resting your eyes. However, you should not leave it on overnight or when you are away for more than an hour. Even switching to sleep or standby mode or sending your PC to hibernation mode can help save energy. 

Put Your PC in Sleep

Putting your PC in sleep or standby mode will significantly decrease its power use. While a full PC uses around 200 Watts of electricity, a PC that is in sleep mode will use around 5 Watts – almost 40 times less! Regardless of the significant savings, you can make, you should leave your computer in sleep or standby mode for prolonged periods of time, such as a full week or while you are on vacation. 

While some people may use sleep mode to decrease the time their PC needs to boot up, it is much better to use hibernation mode. This mode will completely shut down the PC or laptop but will still enable fast boot time whenever you start it. Beware that turning off your PC periodically is still necessary, as it will prevent damage to the operating system. 

Turn Off Connected Devices When Not Used

Printers, cameras, IP cameras, routers, modems, and any other connected peripherals will draw power whenever connected to your computer but are not in use. For this reason, you should turn them off. Turning them off can save several dozens of vampire Watts – the invisible energy use that could be used to power 60,000 households in the UK alone. 

Switch to Laptops

Switching to laptops is probably the next best thing you can do to reduce your energy use. A laptop uses less than 50 Watts of power, even when used to the maximum potential. Every basic calculator will be able to tell you that how many watts a laptop is using is still less than what a PC could use. If in doubt, use a watt meter and see for yourself how many watts your laptop draws when in use – this is the most accurate method, after all. Please bear in mind that gaming laptops may use more energy, especially when gaming. 


Should I shut down my PC every night?

Yes, you should shut down your PC every night. Your PC will keep consuming power, even when left with nothing to do. Dimming your screen may reduce energy use, but you should bear in mind that your tower will keep using energy – up to one kilowatt-hour for every five hours it is left on. It takes a few seconds to shut down a laptop and a few seconds to turn it back on. 

How do I choose a PC power supply?

To choose your PC power supply, you should use one of the software solutions to check the energy use of every individual component, such as your graphics card. Once you have them all, sum the usages and add around 30-50% of that number on top of it for future expansion. Consider that the best power supply will always leave some wiggle room for your components’ power supply. 

Is it OK to leave the PC on overnight to download?

Yes, it is OK to leave your PC on overnight to download. While this increases your power usage, you can always dim the screen and turn off and unplug all connected peripherals. This will decrease energy use, while you will be able to keep downloading your materials. It is important to shut down your PC when there is nothing to do overnight. 

Is switching off at the wall the same as unplugging?

Yes, switching off the wall is the same as unplugging. However, you should not do this very often, as completely shutting down your computer means that no power is being drawn from the socket. You should only unplug your computer during storms or when on vacation – to protect the delicate equipment from power surges and other grid instabilities. 

Conclusion there are different methods to measure how much energy your computer is drawing from the grid, the most reliable one seems to be the direct measurement by a watt meter. This simple device has an error margin of only 5% and will be able to tell you precisely how much power you’ve used, even over longer periods of time. The way you use your laptop or PC, different components that are in it, and other factors, such as extra features you may get from PCI cards, all increase power consumption, so being aware of how you use your PC can have a big say on how you can save energy when running your computer. 

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