2021 Electricity Cost Calculator

Estimate the cost of electricity usage given the power consumption and time the appliance or device is on. Learn about the power consumption of common appliances.

note: the average price per kWh is 12 cents

Electricity Cost Estimate:

Current Cost per Month


Total kWh per Month

14.40 kWh

How to Estimate Electricity Cost of Using an Appliance or Device

Homes these days are equipped with many appliances, and we use dozens, if not hundreds, of other devices making it difficult to predict energy usage. The easiest way to estimate electricity consumption and how much each appliance and device costs on your electric bill is to use the calculator above.

Continue reading to learn some easy formulas to calculate this yourself.

Electrical power lines in the sunset

Step One: Calculate the Energy Used in Kilowatt-Hours

The first step to estimating energy usage and costs is to calculate the kilowatt-hours (kWh) of energy used. Kilowatt-hours are a measurement of the power in kilowatts consumed in one hour.

To calculate kWh, start by finding the power consumption of the appliance in watts. This could be marked on the device, in the owner’s manual, or in the technical specifications.

Next, multiply the power in watts by the hours used per day, then divide by 1,000 to get the kilowatt-hours used.

The kilowatt-hour usage formula is:

kWh = P(W) × T(h/day) ÷ 1,000(W)

Step Two: Calculate the Electricity Cost

To find the price for the kWh used, multiplying by the cost per kWh charged by the electric company by the kilowatt-hours measurement found above.

Electricity costs vary, but the national average electricity cost is $.12 per kilowatt-hour. This cost is shown on the monthly electric bill from the power company.

The electricity price formula is:

Price = Electricity(kWh) × Cost(price/kWh)

For example, find the electricity cost per month to run a computer with a 400w power supply that is running 4 hours per day.

Find the kilowatt-hours:

kWh = P(W) × T(h/day) ÷ 1,000(W)
kWh = 400 W × 4 hrs ÷ 1,000
kWh = 1.6 kWh

Calculate the cost:

Price = Electricity(kWh) × Cost(cost/kWh)
Price = 1.6 kWh × $.12
Price = $.19 per day

Monthly Price = $.19 per day × 30
Monthly Price = $5.70

It would cost $5.70 per month to power the average computer for only 4 hours per day.

It’s also possible to use this formula to find out how much a light bulb or light fixture costs per month. Use our lighting cost estimator to find out how much lamps and light bulbs cost to keep on for the month and to find out how much money can be saved by upgrading to LED light bulbs.

Power Consumption of Common Appliances

Power consumption of common household electrical devices and appliances
Appliance / Device Power Consumed
air conditioner 2000W – 4000W
baseboard heater 1500W
portable heater 1500W
garage heater 4000W
refrigerator 150W – 350W
deep freezer 100W – 350W
oven 2000W
stove 1000W
dishwasher 1200W – 1500W
clothes washer 500W
clothes dryer 4000W
desktop computer 200W
laptop computer 50W
LED TV 20W – 60W
LCD TV 90W – 250W
plasma TV 260W – 340W
LED light bulb 7W – 10W
fluorescent light bulb 16W – 20W
60W incandescent light bulb 60W
ceiling fan 25W – 75W
table fan 10W – 25W

Our voltage drop calculator can calculate a drop in voltage, minimum wire size, and maximum wire length for your electrical project.