Calculating Energy Consumption (Tips and Information)

Calculating Energy Consumption

Energy Consumption is the amount of energy a device consumes while it is on or in use.

The device can be a TV, light bulb, Game Cube, or even a Refrigerator.

The consumption is in watts or kilowatts the device will use in the number of hours each day. Let’s go into more details on how it is measured:

What is the Formula

The consumption formula is as follows:

E(kwh/day) = Pw x t(h/day)/1000W/kw

Definition of each element of the calculation

The Elements in the equation are defined as:

E stands for Energy.

KWH stands for kilowatt hours.

KWH/day stands for kilowatt hours per day

P stands for power.

W stands for watts.

T stands for the number times a device is used in a day.

H stands for the number of hours.

KW stands for kilowatts.

How to do the calculation

Example 1

Before you can calculate, you must choose a device that you want to use.

If you choose a microwave, you need to find if it consumes its power in kilowatts or watts. In this example, it is 800 watts. Now you must decide how many hours you use the microwave in a day.

Let’s say you use your microwave 5 hours each day. The equation should look like this: 800 x 5/1000 = 4. This makes the total energy consumed by the microwave to be 4 KWH per day.

What if you wanted know the total KWH per month?

How about in a year? All you would need to do is multiple 4 KWH by 30 or however many days in a month.

This would calculate as 120 KWH each month. To calculate per year, multiple the 4 KWH by 365.

This calculates as 1460 KWH, which be the total KWH per year. (As long as you use your microwave for only 5 hrs per day.)

Example 2

Let’s calculate the energy consumption of a laptop computer that is used 16 hours per day.

The power consumption is 50 watts. The equation should look like this: 50 x 16/1000 = 0.8 KWH per day. At 16 hours each day for a month, the total is 24 KWH. And for a year, it is 292 KWH.


If you are having trouble finding out the power consumption of your device (in kilowatts or watts), make sure to look at the label on your device.

You should also check the user manual. In the worse case scenario, you can always use the model number find the power consumption on the internet.


Pay close attention to the power consumption of the device you are trying to calculate.

If the device’s power consumption is in kilowatts, you will not need to divide by the 1000 when you are using the formula.

If the device power consumption is in watts, then you will need to divide by 1000 as the energy consumption equation is in KWH. For every 1000 watts, there is 1 kilowatt.

Calculating Energy Consumption (Tips and Information)

That is why it is important to divide by 1000 if the power consumption is in watts.

Now that you know how to calculate the energy consumption of any device in watts or kilowatts, it should be much easier to understand your energy bill.

You should try calculating the energy usage in your home and compare it to your bill. Maybe, you will find a way to optimize your total energy consumption.

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