Electricity Cost Calculator

This electricity cost calculator works out how much electricity a particular electrical appliance will use and how much it will cost. This calculator is a great way of cutting back on your energy use and saving on your electricity bills.

How to use this calculator:

  1. Input what you pay for energy per kilowatt hour.
  2. Input how many days there are in the month you want to calculate for.
  3. Choose your appliance. The "Wattage (W)" field will be filled in automatically on the basis of the appliance you choose. You can input your own value if you wish. This will usually be printed on the appliance's nameplate in watts (W) or kilowatts (kW). The listed wattage is the maximum power the appliance can draw. Wattage (watts, W) = Current (amperes, A) × Voltage (volts, V).
  4. Input how many appliances you will be using.
  5. Input how many hours a day an appliance runs.
  6. To add a new appliance, press the "+ Add Appliance" button.
Online Electricity Cost Calculator

 Enter the price of energy per kilowatt-hour

 Enter number of days in month

Appliance # of Appliances Wattage (W) Hrs per Day kWh Cost x
Daily Monthly Daily Monthly

What is a kilowatt hour (kWh)?

A kilowatt-hour (kWh) is a way of measuring the amount of energy you're using.

One kilowatt-hour is equal to how much energy that would be used by keeping a 1000 W appliance running for 60 minutes, so for example, if you left a 50 W appliance running, in 20 hours it would use 1 kWh of energy.

Formula & Example

Energy use in kilowatt-hours is determined by multiplying the number of hours appliance operates by its rated power in kilowatts.

We then multiply the electricity cost per kilowatt hour to calculate what it costs to keep the appliance running.

Thus, we use the following formula:

Wattage in Watts / 1,000 × Hours Used × Electricity Price per kWh = Cost of Electricity

So, for example, if we have a 40 W lightbulb left on for 12 hours a day and electricity costs $.15 per kilowatt-hour, the calculation is:

40 watts / 1,000 × 12 hours × $.15/kWh = $.072


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