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Power, voltage and current


1. What are Power, voltage and current

2. Power, voltage and current calculators

3. Plug in power meter

4. Energy conservation

4.1. Proven ways to save electricity at home

What are Power, voltage and current

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 (I) 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 and current will let us determine the Power in Watts or Kilowatts and that knowledge does already allow 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.

What is a Kilowatt hour (kWh)

Power, voltage and current calculators

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 and electricity cost calculators‘ page that may be of your interest:

Plug in power meter

If you want to know the exact power or electricity usage of an appliance or device, your best option is to use a plug in power meter.

The image below it will redirect you to the Amazon page where you can have a look to the specifications of the power meter we use for our measurements.

plug in power meter

All of our house appliances and devices like the washing machine, the dishwasher, the TV or the printer are plugged to a wall socket. 

So, with a power consumption meter we can determine how much electricity our appliances or devices are using and, more importantly, we can measure the electricity usage over a period of time.

If you want to find out how you can use a plug in power meter to measure your electricity usage and electricity cost, have a look to this YouTube video.

Plug in power meter

Energy conservation

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 day (0,01 kWh) that would add to 32850 Kilowatt hour (kWh) saved per year. 

9000 households x 0,01 kWh per day x 365 days per year 

32,850 kWh saved 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) per kWh, we would collectively be saving nearly 6000 euro per year.

> To produce 32,850 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.

Proven ways to save electricity at home

If you are looking for ideas to save electricity at home, have a look to this YouTube video were we show some useful tips to reduce the electricity usage at home and decrease the electricity bill. 

How to save electricity at home
How to save
How to save
How to earn
How to earn


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