- What is Power (P), Voltage (V) and Current (I) -

Here we are going to have a look to what Power (P), Voltage (V) and Current (I) are and how this knowledge can help us to find out our household devices and appliances electricity usage and electricity cost. 

Power (P) it is the measure of the rate at which energy is delivered or used by our household appliances. Power is equal to the voltage multiplied by the current.

P = V x I

Voltage (V) is the difference in electric potential between two points. Without going into technicalities, take that for some countries the household appliances and devices use 220 Vdc while some other countries use 110 Vdc. Voltage is equal to power divided by current.

V = P / I

Current is the measure of the flow of electric charge through a material. Again, trying to keep it simple, the amount of current drawn is one of the two factors that determine the energy/power used by a household appliance or device. Current is equal to power divided by voltage.

I = P / V

Voltage a current will let us determine the Power in Watts or Kilowatts and that knowledge does already enable us to progress further with figuring out the household appliance and devices electricity usage.

The following video explains what a Watt (W), Kilowatt (kW) and Kilowatt hour (kWh) are and how this knowledge can help us to find out our households appliances and devices electricity usage and electricity cost. 

Do not forget to enable the video captions, as the video caption contains the concepts explanations.

Electricity usage and cost calculator

This calculator can be used to:

– Calculate Power (P) from Voltage (V) and Current (I).

– Calculate Wattage

-Calculate Watts

P = V x I


This calculator can be used to:

– Calculate Voltage (V) from Power (P) and Current (I).

V = P/ I


This calculator can be used to:

– Calculate Current (I) from Power (P) and Voltage (V).

-Calculate Amps

-Calculate Amperes

I = P / V


A few other examples from our ‘Electricity usage calculators‘ page that may be of your interest:

Fridge electricity usage calculator
Freezer electricity usage calculator
Dishwasher electricity usage calculator
Coffee machine electricity usage calculator
Coffee machine

Additional information

A very practical way to find out how many watts, kilowatts or kilowatt hours of electricity do our household appliances use, it is to use a plug in power meter.

A plug in power meter do also measure the exact electricity cost over time so this device can be used to find out how much you are paying and find any appliance or device which may be wasting electricity.

All our videos can be found in YouTube, in both English and Spanish languages.

If you are looking for saving electricity at home, have a look to this video where we provide some useful tips to reduce the electricity consumption and decrease the electricity bill.

Electricity conservation - Save and conserve energy

Energy conservation can be defined as the decision and the act of using less energy

Energy conservation both benefit you and the environment

The act of saving and conserving electricity does benefit you because you will be paying less on your energy bills. 

And it also does benefit the environment because conserving electricity prevents any unnecessary waste of natural resources.

Now, at individual level it may not look worth to try to save a few watts here or there. 

Still, every little counts and if hundreds or thousands of us do save a little every time, it will make an important contribution towards conserving our natural resources.


For example, if 9000 households would manage to save as little as 10 Watts per hour (0,01 kWh) worth of electricity per day, that would add to 32850 Kilowatt hour (kWh) per year. 

That is a considerable amount of electricity, but let’s add additional perspectives for clarity:

  • Assuming an average cost of 0,18 euro (or dollars, or pounds, or any other currency) we would collectively be saving nearly 6000 euro per year.
  •  To produce 32850 kWh of electricity it is necessary to use around 17 metric tons of coal or 56 barrels of residual fuel oil.
Have a look to this page for more information about the amount of resources needed to produce electricity.

In any case it is clear that small energy savings do really count when looking into the bigger picture.

We hope that you have found the information on this page informative and of value. 

If so, please consider to share or subscribe to our newsletter.

We dedicate a considerable amount of time and effort to create content and your support and engagement will encourage us to keep moving forward.

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Effiworkx blog

For more useful energy and water saving information and advice, have a look to our blog.

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