# How much electricity does a computer use ?

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In this article, we have explained how much electricity does a computer use with detailed calculations to arrive at the annual cost and Electricity consumption as well.

On average, a Desktop Computer uses **219 Watt per hour of Electricity** while a 15 inch Laptop uses **159 Watt of Electricity**. We have provided detailed calculation to arrive at the total Electricity consumption and Cost.

**Table of contents**:

- Electricity consumption of Desktop Computer
- Electricity consumption of Laptop
- Conclusion

## Electricity consumption of Desktop Computer

The CPU and Desktop monitor consumes around **170 Watt per hour** of Electricity when actively used. On standby mode / sleep mode, the power consumption goes down to **80 Watt per hour**.

There are other devices that are used along with a Desktop Computer which uses power. This needs to be considered in our calculation. Other devices include:

- Speakers which consume upto 20 Watt per hour
- Printer and Scanner which consumes upto 7 Watt per hour
- Internet Modem which consumes upto 10 Watt per hour
- Paper Shredder which consumes upto 12 Watt per hour

This brings the total consumption to 219 Watt per hour.

```
Total = 170 + 20 + 7 + 10 + 12
= 219 Watt per hour
```

If you wish, you may include the power consumption of a medium Air Conditioner as you need to keep your Desktop cool and avoid overheating. A medium Air Conditioner will consume upto 1000 watt per hour. We will avoid this in our calculation as it is not a component of computer.

Let us assume that you use your Desktop actively for 9 hours a day and you keep the computer in stand-by mode for 4 hours a day. This brings our daily power consumption to **2072 Watt per day**.

```
Daily = 219 * 8 + 80 * 4
= 2072 Watt per day
```

This brings the total power consumption per year to 765 KW per year assuming you use your Computer everyday. Ideally, the total will be slightly less provided you may not use your Computer everyday / weekends.

```
Yearly = 2072 * 365 = ~ 765 Kilo Watt per year
```

The average cost of Electricity in USA is **12 cents per Kilo Watt per hour**. The actual value depends on your location. With this, the total cost of running a Desktop computer will be:

- $0.25 per day
- $91 per year

## Electricity consumption of Laptop

A Laptop consumes much less power compare to a Desktop Computer. The Electricity consumption of Laptop is 70 Watt per hour when on active use. On stand-by / sleep mode, the electricity consumption of Laptop goes down to 25 Watt per hour.

We will consider the same external components:

- Wireless mouse which will consume upto 5 Watt per hour
- A second monitor which will consume upto 35 Watt per hour
- Speakers which consume upto 20 Watt per hour
- Printer and Scanner which consumes upto 7 Watt per hour
- Internet Modem which consumes upto 10 Watt per hour
- Paper Shredder which consumes upto 12 Watt per hour

This brings the total consumption to **159 Watt per hour** for Laptop.

```
Total = 70 + 5 + 35 + 20 + 7 + 10 + 12
= 159 Watt per hour
```

Let us assume that you use your Laptop actively for 9 hours a day and you keep the computer in stand-by mode for 4 hours a day. This brings our daily power consumption to **1372 Watt per day**.

```
Daily = 159 * 8 + 25 * 4
= 1372 Watt per day
```

This brings the total power consumption per year to **500 KW per year** assuming you use your Laptop everyday. Ideally, the total will be slightly less provided you may not use your Laptop everyday / weekends.

```
Yearly = 1372 * 365 = ~ 500 Kilo Watt per year
```

The average cost of Electricity in USA is **12 cents per Kilo Watt per hour**. The actual value depends on your location. With this, the total cost of running a Desktop computer will be:

- $0.16 per day
- $60 per year

## Conclusion

As a conclusion,

- A Desktop uses 765 KW of Electricity per year which costs $91.
- A Laptop uses 500 KW of Electricity per year which costs $60.

A Laptop uses 35% per Electricity compared to a Desktop Computer. The exact power consumption depends on the model of Computer you are using but the range will remain close as vendors aim to optimize power consumption.

Assume you run a Company with 100 employees and you provide dedicated laptop to each. Then, you will be spending $6000 per year on Electricity bill to run the Laptops contributing to **50 Mega Watt of Electricity consumption**.

With this article at OpenGenus, you must have the complete idea of how to calculate Electricity consumption of a Computer.