2018 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.

How to Estimate Electricity Cost

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. Learn how much each appliance and device costs to power by calculating the electricity usage.

Energy costs can be found by finding the total wattage used, multiplying by the hours used per day, then dividing by 1000 to get the kilowatt hours (kWh) used. Find the price for the kWh used by multiplying by the cost per kWh charged by the electric company.

The kilowatt-hour usage formula is:

P_(W) × T_(h/day) / 1000_(W/kW)

The total price formula is:

Electricity_(kWh) × Cost_(cost/kWh)

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.

Let’s try an example to understand the formulas. If we have a computer with a 400w power supply, we can find the cost per month to keep the computer running for 4 hours per day. We start with 400w x 4h / 1000, which equals 1.6. The next step is to multiply by the kilowatt per hour cost, 1.6 * .12, which equals $.19 per day. The monthly cost of this requires us to multiply by 30, $.19 x 30 = $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

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