How Many Amps Does a Computer Use? A Guide to Efficient Energy Use

The way modern offices and households use computers, laptops, tablets, etc. indicates that the dependency on these gadgets isn’t going to decrease anytime soon. So, the concerns about electricity consumption are valid and quite a matter of consideration, especially when energy efficiency has become a popular term in our daily life.
Less consumption means lower utility bills which ultimately lead to more saving. You can’t really begin an energy efficiency initiative without knowing the amount a computer requires for its regular operations? So, how many amps does a computer use?
The answer is 3-5 Amps @ 120 VAC. Is that all? No, but, this is at least the most common answer that you may get after googling “how many amps does a desktop computer use?” From a technical point of view, several things factor into the calculation of a computer’s energy consumption.
What Factors in a Computer’s Consumption of Electricity?
The configurations of a PC and the way one uses the device are the deciding matters. Let’s get a hold of these and then move forward with the actual amps that a computer pulls.
Configurations and Components of a Computer
There’re many possibilities as to how you configure your computer. Your budget, needs, and availability of the hardware components are some of the crucial aspects of purchasing a machine. For personal uses, a low-end unit may suffice while people with interests in using their computers for professional applications would look for a little higher end.
Offices and organizations that carries out a lot of internet-based activities often tend to the latest generations of PCs.
The general rule here is that more powerful hardware setups require a higher amount of power than the ones with a basic profile. It means a writing professional who doesn’t rely on the photo and video editing tools may not look for higher configurations, but an animator or graphic designer would.
Similarly, a gamer usually wishes to have a decent setup, but those who keep a computer for strictly personal applications like entertainment purposes may not spend too much on higher performance.
User Behaviors
How long a computer is in operational mode is another aspect that contributes to its overall power consumption. If your PC is in use for as long as eight hours a day, the power it pulls would be higher than the one in use for just a few hours. Whether or not a computer on the stand-by mode requires power creates a misconception. The truth is that stand-by units pull one-third of the amount required by the busy ones.
Power Consumption of Computers and Laptops
When it comes to ‘laptop versus desktop’, the most obvious points of argument include performance, usability, price, repair cost, etc. But, the rate of energy consumption is also significant, and you’ll acknowledge it when you’ll read the following discussion.
Laptop computers aren’t as demanding as desktop PCs. Being smaller in look and design, laptops consume up to 80% less power than desktops. With small Power Supply Units (PSUs), laptop computers are always more energy efficient. However, the devices that draw higher amounts of energy may consume as much electricity as their desktop counterparts that consume low energy.
How Do You Calculate the Consumption?
It’s time to check your computer’s PSU to find the wattage rating. You can also look at the PSU module or the user manual. To calculate the amperage your PC is pulls as it’s in use, follow the method below.
Watts (Adapter rating)/Voltage = Amps
So, the amps a computer use should be 2.5 if the power supply comes rated at 300 Watts. Look at this calculation: 300 watts / (line voltage @ 120 volts) = 2.5 amps.
There’s a way to understand if your PSU relies on higher or lower energy consumption.
Try to count the number of fans inside your Central Processing Unit (CPU). If you see there’s just a single fan and no cooling component, the unit runs on a small amount of power. Contrarily, you may find several fans with an active cooling system, the machine requires a higher amount of energy to run. Common PSU modules come rated at different watts such as 100W and 200W for low-end PSUs and 300W, 500W, 750W, and 1000W for high-end PSUs.
So, How Many Amps Does a Desktop Computer Use?
The amps that computers draw fall anywhere between 0.25 and 2 or more. A desktop PC uses up to 1.67 amps per hour with the printer and speakers running. So, a computer that runs as long as eight hours a day needs up to 5 amps.
Since we know modern users have to rely on a number of output and input tools other than the computer itself, the amps a computer takes aren’t consumed entirely by the unit. Here’s a breakdown of the consumed amount.

  • The computer uses almost 1.43 amps per hour on average. The consumption may go up to 2 amps or even higher at 100% workload.
  • An internet connection device/modem 0.083 amp per hour.
  • A printer consumes 0.04 amp per hour.
  • The loudspeakers need 0.17 amp per hour.

There’re significant deviations from the above estimates when it comes to workstation computers which usually consume 2 amps to 3.50 amps per hour when performing at 100% and 0.75 amp to 1.20 amp per hour when at rest.
How Many Amps Does a Laptop Computer Use?
As already discussed, laptop devices are known for their low energy consumption. A typical device uses anywhere between 0.41 amp and 0.84 amp per hour, which can be just one-third to half the amount required by desktop computers. So, a laptop if used for eight hours a day consumes up to 6.73 amps including the complex multi-tasking sessions.
The above estimates seem too plain to be applicable for many users. You may have a gaming desktop or laptop. Even, you might have a very special monitor that stands out with enriched engineering. Here’s another overview of the power consumption by gaming PCs, Mac, and different computer monitors.
How Many Amps Does Gaming Computer Use?
Gaming PCs are often considered the beast that typically includes a 750W power supply module and cutting-edge components for richer graphics. So, it isn’t overwhelming to discover that a gaming desktop that has a PSU rated at 750 watts consumes as many as 6.25 amps an hour and 31.25 amps for five hours of gaming experience. For a gaming laptop, the required amps can be 15.80 or higher for five hours of gaming experience. Beginners might need to seek tips on how to play leagues and learn about setting up their computers for gaming efficiency.
How Many Amps Does a Mac Computer Use?
Mac PCs and MacBook devices are known for their energy-efficient power supply modules.
A decent model that sports a 27-inch display and comes with a 2.66GHz Quad-core Intel i5 processor and ATI Radeon 4850 graphics consumes 1.21 amps an hour when idle and 3.04 amps/hour while running at its peak.
A low-end Mac that comes with a 21.5-inch display with 16GB 2400MHz DDR4 SDRAM and no remarkable graphics profile takes only 0.28 amp/hour when idle and 0.62 amp/hour when operating at its best.
The same energy-efficient factor applies to the MacBook devices which usually consume a maximum of 0.72 amp/hour, 0.04 amp/hour when idle, and 0.01 amp/hour when in a sleeping mode.
How Many Amps Does a Computer Monitor Use?
Computer monitors are crucial to energy consumption. Desktop monitors that we usually see need 0.15 amp to 0.5 amp tops. The calculation for CRT monitors or LED-backlit screens will be a little different from ordinary monitors or computer screens. For example, a 22-inch LED-backlit LCD monitor consumes up to 0.30 amp for five hours.
Tips to Ensure Energy Efficiency
By now, you’ve got the long and short of the energy demanded by computers. What’s next? You want to get some insights into the approaches to energy efficiency, don’t you? Well, below are quick tips that should help you.

  • Disconnect the external devices when you don’t need them.
  • Remove the peripherals (the ones you don’t need right away) from your home servers.
  • Use a smart strip and plug the equipment into it, especially when you don’t want to or can’t turn the computer off.
  • Customize your computer’s power management settings.
  • Use browsers and applications that consume less energy while serving you well.
  • Adjust settings so that the PC shuts down automatically at a certain time when you don’t usually use a PC but chances are that it’s turned on.
  • Use smart, uninterruptible PSU modules if you don’t want to shut down the system.
  • Don’t forget to shut down the machine when you’re sure you’re done for the day.
  • Don’t keep your laptop charger plugged into the power source when you need not have the device charged. You may use a timer for the charger.
  • Try to buy PCs and associative hardware components that are compliant with the Energy Star rating.

Following these suggestions, you can reduce your computer’s demand for power by as much as 20%, which can have a direct impact on your monthly electricity bills. Moreover, disciplined and planned usage of the PC may enhance the longevity of its hardware parts allowing you to enjoy years of good performance.