Electricity Cost Calculator - Appliance Cost Per Month

The formula

Cost = watts × hours used ÷ 1,000 × price per kWh. Dividing by 1,000 turns watt-hours into kilowatt-hours, the unit on your electric bill. A 1,500-watt space heater running for one hour uses 1.5 kWh. At 18 cents per kWh, that hour costs 27 cents.

Everything else is scaling. Multiply by hours per day, then by days used per week ÷ 7 to get a daily average, then by 30.4 for a month or 365 for a year. The calculator does this for every appliance you add, sorts them by cost, and tells you which one is the biggest drain.

Finding the numbers

Watts are printed on the appliance's nameplate or power adapter, usually on the back or bottom. If only amps and volts are listed, multiply them: a 10-amp, 120-volt appliance draws up to 1,200 watts. The U.S. Department of Energy notes that nameplate figures are maximums, so real use is often lower.

Your electricity rate is on your bill. Divide the total charge (including delivery fees and taxes) by the kWh used to get your all-in rate. The U.S. Energy Information Administration reports the national residential average at 18.3 cents per kWh in July 2026, but it ranges from about 12 cents in parts of the South and Mountain West to over 30 cents in California, New England, and Hawaii. That spread matters more than almost any other input.

For the most accurate reading, plug the appliance into an inexpensive plug-in watt meter for a few days. It measures actual kWh, which is the only honest way to measure things that cycle on and off.

Worked example: space heater, fridge, and TV

A 1,500-watt space heater used 4 hours a day uses 6 kWh a day, or 182.5 kWh a month. At 18 cents that is $32.85 a month and $394 over a year of daily use. That is why space heaters surprise people on their winter bills.

A refrigerator is different. Its compressor cycles, so the calculator uses an average draw of about 60 watts over 24 hours: 1.44 kWh a day, 526 kWh a year, about $95. Check the yellow EnergyGuide label for your model's rated kWh per year; newer ENERGY STAR fridges often use less, while a 20-year-old garage fridge can use double.

A 100-watt TV on 5 hours a day is 0.5 kWh a day, or about $33 a year. Small, but they add up: phantom loads from devices on standby can be 5 to 10% of a household's electricity use.

What actually moves your bill

Anything that heats or cools is expensive: space heaters, electric water heaters, dryers, ovens, and air conditioning. A Level 2 EV charger drawing 7.2 kW for 90 minutes a day adds about 10.8 kWh daily, roughly $710 a year at 18 cents, which is still usually far cheaper than gasoline for the same miles. Lighting and electronics rarely matter individually. Swapping a 60-watt incandescent for a 9-watt LED on 5 hours a day saves about $17 a year per bulb, which is real money across a whole house.

If your utility has time-of-use rates, the time of day matters too. Running the dryer or charging an EV overnight at an off-peak rate can cut those costs by a third or more. Enter the off-peak rate to see the difference.

Common mistakes

Using the nameplate for cycling appliances. A fridge rated 700 watts does not use 700 watts all day. Use the EnergyGuide label or a meter.

Using only the energy charge. Many bills split supply and delivery. The rate that matches your real cost is the total bill divided by total kWh.

Confusing watts and watt-hours. Watts are the rate of use; kilowatt-hours are the amount. Your bill charges for the amount.

When to call an electrician or an energy auditor

If your bill is far higher than the calculator suggests, something is likely using power you have not accounted for: an old electric water heater, a failing well pump, a pool pump running around the clock, or electric resistance backup heat kicking on in a heat pump system. A home energy audit (many utilities offer them free or at low cost) will find it. Call a licensed electrician if an appliance's cord or outlet gets hot, or if breakers trip when big loads run together.