How to calculate electricity cost
Electricity cost depends on the amount of electrical energy used and the price charged for each kilowatt-hour.
To estimate energy from an appliance power rating, convert watts to kilowatts and multiply by operating time.
Electricity cost example
A 1000-watt appliance is equal to 1 kilowatt. If it operates for 8 hours per day, it uses approximately 8 kWh each day.
If it operates for 30 days, monthly energy use is 240 kWh. At a rate of 0.15 per kWh, the estimated monthly energy cost is 36.00 in the selected currency.
Watts, kilowatts and kilowatt-hours
A watt is a unit of power. 1,000 watts equals 1 kilowatt. Power describes the rate at which an appliance uses or transfers energy.
A kilowatt-hour is a unit of energy. One kilowatt-hour is the energy used by a 1 kW load operating for one hour.
Multiple appliances
The quantity field lets you estimate several identical appliances together. Their combined connected load is the power of one appliance multiplied by the quantity.
For example, four 100-watt devices represent a combined load of 400 watts, or 0.4 kW.
How monthly energy use is calculated
The calculator first finds daily energy from total connected load and hours used per day. It then multiplies that value by the entered number of operating days per month.
The 12-month estimate multiplies the entered monthly usage pattern by 12. It therefore assumes the same number of operating days and the same electricity rate each month.
Electricity rate per kWh
Electricity prices differ by utility, tariff, location, usage tier and time of use. Enter the rate that applies to your own situation rather than relying on a generic national price.
The currency selector only changes how results are displayed. It does not perform currency conversion and does not look up electricity rates.
Rated power vs. actual power consumption
The power printed on an appliance label may represent a rated, maximum or typical value rather than a constant measured load.
Devices with thermostats, compressors, variable-speed motors, sleep modes or changing workloads can draw different power at different times. Measured average power may give a better estimate when it is available.
Electricity cost and amps
If you know current and voltage but not power, you may first need to estimate watts. Use the Amps to Watts Calculator for that conversion.
To calculate current from a known wattage, use the Watts to Amps Calculator.
For voltage, current and resistance relationships, use the Ohm's Law Calculator.
This calculator estimates energy charges from the power, operating time and rate you enter. A real utility bill can also contain fixed charges, taxes, demand charges, tiered pricing, time-of-use pricing, fuel adjustments or other fees that are not included here.
Frequently asked questions
How do I convert watts to kWh?
Divide watts by 1,000 to convert to kilowatts, then multiply by the number of operating hours.
How much does a 1000-watt appliance cost to run?
A 1000-watt appliance uses 1 kWh for every hour it operates continuously. Multiply that energy by your electricity rate per kWh.
Does the calculator know my electricity rate?
No. Enter the rate from your own tariff or electricity bill so the estimate reflects your situation.
Are taxes and fixed utility fees included?
No. The result estimates energy charges from kWh and the entered rate. Other utility charges are not automatically added.
Can I calculate several identical appliances?
Yes. Enter the number of appliances and the calculator combines their power before calculating energy and cost.
Using this calculator effectively
The Electricity Cost Calculator estimates energy consumption and operating cost from appliance power, quantity, hours of use, operating days and the electricity rate you enter. Results include daily, monthly and 12-month kWh and cost.
Common uses
- Estimating how much an appliance may cost to operate each day or month.
- Comparing electricity use for several identical devices or different usage schedules.
- Converting appliance power and operating time into estimated kilowatt-hours for budgeting.
Tips for a better estimate
- Use measured average power when available because an appliance's rated wattage may not equal its continuous real-world consumption.
- Enter the electricity rate that applies to your own tariff because prices and billing structures vary by utility and location.
- Remember that fixed charges, taxes, demand charges, time-of-use pricing and other bill items are not included in the simple kWh cost estimate.
Related calculations
Amps to Watts Calculator · Battery Runtime Calculator · Ohm's Law Calculator