PC Power Consumption Calculation, Formula, Power Saving Tips

PC Power consumption calculator:

Enter the PC watts (you can get it from nameplate), operating hours and the per-unit rate to get the power consumption and the electricity bill per day, per month and per year.

By default, we have added 140 watts with the operating hours of 18. By pressing the calculate button.

Enter Hours Used Per Day: Hr
Enter PC Wattage: W
Per Unit rate:  
Energy Per Day: kWh
Energy Per Month: kWh
Energy Per Year: kWh
Cost Per Hour:  
Cost Per Day:  
Cost Per Month:  
Cost Per Year:  

Pc power consumption Formula:

PC power consumption E(kWh) in kWh (kilo Watt hour) is equal to the rating of the PC in watts’ times of the total working hours in hr divided by 1000. Hence PC power consumption formula can be written as

Total power consumption = PC Watts x Running Hours / 1000.

Note that, you can take the PC wattage from the nameplate details.

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Sometimes, the manufacturer shall provide the PC input current and input voltage. During that time, you may need to calculate the total watts.

Here the total PC watts is equal to the product of the input current in Amps and input voltage in volts.

Hence the formula can be written as,

Total power consumption = input volts x input current x Running Hours / 1000.

The above formula can be used for calculating PC power consumption for a single day,

In case if you want the power consumption monthly and annually means, you have to use the below formula,

Per month:

E (kWh – Monthly) = 30 x PC Watts x Running Hours / 1000.

E (kWh – Monthly) = 30 x input volts x input current x Running Hours / 1000.

Per year:

E (kWh – Yearly) = 365 x PC Watts x Running Hours / 1000.

E (kWh – Yearly) = 365 x input volts x input current x Running Hours / 1000.

Pc power consumption calculation:

Let we take an example of Lenovo Idea Centre A340-22 model PC and calculate the power consumption per day, per month, and per year.

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According to its datasheet, the Lenovo A340-22 model PC consumes 130 watts. It means, the PC consumes 130 Watts for one hour.

Apply our formula,

PC Power Consumption Calculation – 24 Hours
 Consumption Total (Wh) kWh Cost
Hourly 130 0.13 0.39
Day 3120 3.12 9.36
Month 93600 93.6 280.8
Yearly 1138800 1138.8 3369.6


Here we have considered 3.00/- as per unit rate.

Gaming PC power consumption components:

Typically Gaming PC consumes 300% extra than the normal PC. Since gaming PC will be built with the larger size components.

Let we taken an ASUS gaming PC consumes 350 Watts per hours and you are playing the game 18 hours per day, hence calculate the power consumption per day, per hour, per month and the electricity cost per hour, per day, per month and per year. Consider electricity bill as 3.00 per unit.

Gaming PC Power Consumption -18 Hours
 Consumption Total (Wh) kWh Bill
Hourly 350 0.35 1.05
Day 6300 6.3 18.9
Month 189000 189 567
Yearly 2268000 2268 6804
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Now let we move the topic towards power saving.

First off all you must understand the what are all the components involved in power consumption so that you can easily fine-tune it.

Components Involved for Power consumption:

Any PC consists of 8 major electricity parts such as Motherboard, Graphics card, RAM, exhausted fan, Power supply unit, monitor, DVD, Hard Disk and the CPU.

S.No PC Electricity Components
1 Monitor 45%
2 Graphics Card 30%
3 CPU 2%
4 Fan 5%
5 DVD 5%
6 Hard Disk 5%
7 MotherBoard 6%
8 RAM 1%
9 Mouse 0.5 to 1%


Note: The table is prepared based on my personal computer; the percentage of consumption may be varied based on your configuration.

Power saving Tips on PC:

  • Look at the table, the monitor contributes almost 45% of your consumption. The consumption can be reduced by reducing the screen brightness.
  • Graphic card, while choosing the PC, carefully chose the graphics card capacity. Since unnecessary having higher version may lead to higher energy consumption. i.e for normal work, 2 GB GPU is enough. Instead of that, if you choose 6GB means, it consumes extra power for the same work.
  • Choosing the memory: Note that, hard disk come up with the small electric motor to rotate the disk. Hence by choosing the SSD you can totally eliminate the power consumption.
  • Enable sleep mode while the screen is inactive. The best case is, please turn it off when the PC is not required for a long time.
  • Remove/Disconnect the extra devices such as a keyboard, printer, DVD’s, etc.
  • Use LAN cable instead of Wi-Fi. Since Wi-Fi needs external power supply which contributes to your electricity bill additionally on account of PC.
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If you have any idea for PC power saving, please comment us.


  1. Whilst this is good information, please note that the PSU rating has nothing to do with the consumption. You may have a 700 watt power supply, that doesn’t mean it is always using 700 watts of power. It means that it is capable of operating at up to 700w, give or take a small percentage. Therefore this will have very little truth compared to your energy bill.

    • Hi Dave,

      Always we have to take the worst case scenario, which means What if the PSU take full Load? So if it takes less energy then it good.


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