Energy Cost Calculator
Your bill may also carry demand charges, fixed fees and taxes, so treat this as the energy part of the cost.
How the energy cost calculation works
What a piece of equipment costs to run per day, month and year, from its wattage, hours of use and your electricity rate.
Turn watts into kilowatts
Divide the wattage by 1,000. Three 1,200 W heaters draw 3.6 kW together.
Multiply by the hours it runs
3.6 kW for 8 hours is 28.8 kWh a day. Over 22 working days that is 633.6 kWh a month.
Allow for cycling equipment
A fridge compressor might run only part of the time. Lower the full-power share so you don't overstate its use.
Multiply kWh by your rate
633.6 kWh at $0.15 is $95.04 a month. Take the rate from your own bill, since it varies by utility and plan.
Worked example. Three 1,200 W units running 8 hours a day, 22 days a month, use 633.6 kWh. At $0.15 per kWh that costs $95.04 a month, $1,140.48 a year, or $0.54 for each hour they all run.
Energy Cost FAQ
Can I use this as an electricity cost calculator for my bill?
Yes, for one device at a time. Enter its wattage, hours per day and your rate per kWh from your utility bill to see the cost per day, month and year. Add the results to estimate a larger bill.
How do I calculate electricity cost?
Multiply watts by hours used, divide by 1,000 to get kWh, then multiply by your price per kWh. A 1,200 W unit for 8 hours uses 9.6 kWh, which is $1.44 at $0.15.
How do I convert watts to kWh?
kWh = watts × hours ÷ 1,000. A 500 W machine running 4 hours uses 2 kWh.
What is the average cost per kWh?
The US Energy Information Administration puts the July 2026 average at 14.53¢ per kWh for commercial customers and 18.31¢ for residential customers (preliminary figures). At 14.53¢ the default example costs $92.06 a month instead of $95.04. State averages vary widely, so your own bill is the better input.
Where do I find my electricity rate?
Divide the energy charges on your bill by the kWh used in the same period. Some business plans charge different rates by time of day, so use the rate for when the equipment runs.
How much does it cost to run an appliance all day?
Set hours to 24 and lower the full-power share for anything with a thermostat. A 150 W cooler drawing power half the time uses 1.8 kWh a day.
Why is my bill higher than this estimate?
Bills often add fixed customer charges, demand charges based on your peak kW, delivery fees and taxes. This calculator covers only the energy used.
Sources: EIA Electric Power Monthly, Table 5.6.A: average price by sector and state, July 2026 · Energy Saver: Estimating appliance and home electronic energy use