Appliance Electricity Cost Calculator

The formula, and how to get your real rate

Every electricity cost question resolves to the same four-step calculation. Divide the appliance wattage by 1,000 to get kilowatts. Multiply by hours of use per day. Multiply by days per month. Multiply by your rate in dollars per kWh. That is it — a 1,500 W space heater running 4 hours a day for 30 days uses 180 kWh and costs $33.19 a month at the national average rate.

The step almost everyone gets wrong is the rate. Do not use the supply rate printed on your tariff sheet or the number your retail provider advertises, because it excludes delivery charges, grid fees, riders and taxes — the parts of the bill that have been rising fastest. Instead, take the total dollar amount you paid last month and divide it by the kWh the bill says were delivered. The all-in figure is commonly 20% to 30% higher than the advertised supply rate, and it is the only number that tells you what one more hour of running something actually costs you.

For wattage, check the nameplate sticker on the back or underside of the appliance. If it lists amps rather than watts, multiply amps by the circuit voltage: 120 for a standard outlet, 240 for the large outlets used by dryers, ranges, water heaters and EV chargers. For anything with a motor and a thermostat, remember that the nameplate is the draw while running, not an average across the day — which is why the refrigerator preset here uses 150 W, the realistic 24-hour average, rather than the roughly 700 W its compressor pulls while it is actually cycling.

What common appliances cost per month

These figures use the U.S. average rate of 18.44¢/kWh and realistic usage patterns rather than worst-case ones. Seasonal appliances are priced per month of actual use, not annualized, because nobody runs a space heater in July.

• Anything that makes heat or moves heat dominates the bill. Air conditioning, water heating, space heating and clothes drying are four of the five biggest line items in a typical American home.
• Anything electronic is close to noise. Leaving a TV on all day costs less per month than running a space heater for one evening.
• A refrigerator looks cheap per hour but runs 8,760 hours a year, which is why it still lands near $240 annually.

Why space heaters wreck a winter bill

Portable space heaters are the single most common cause of a shocking January electric bill, and the reason is arithmetic rather than any defect in the heater. Almost every plug-in electric heater sold in the U.S. is rated at 1,500 watts, because that is the practical ceiling of a standard 120-volt household circuit. Whether it is a $30 ceramic tower or a $500 designer radiator, it draws the same 1,500 W and produces the same heat — the expensive one is not cheaper to run.

The trap is that a space heater is the least efficient way to heat a house that exists in common use. It converts electricity to heat at 100%, which sounds perfect until you compare it to a heat pump, which moves 250% to 400% as much heat per unit of electricity. A space heater is a sensible way to warm one small room you are sitting in while the rest of the house stays cool. It is a very expensive way to heat a whole floor, and running two or three of them is how people end up with a $300 surprise.

The table shows one 1,500 W heater running 8 hours a day for a month, at rates from the cheapest to the most expensive states.

Electricity rates by state, and why they differ so much

The same appliance can cost four times as much to run depending on which side of a state line it is plugged in on. According to EIA data for May 2026, residential rates ranged from 12.35 cents per kWh in Idaho to 52.00 cents in Hawaii, against a national average of 18.44 cents.

The spread is not arbitrary. The cheapest states run on hydroelectric power built decades ago and long since paid off — Idaho, Washington and much of the Pacific Northwest — or sit on top of cheap natural gas and coal, like Utah, Nebraska and North Dakota. The most expensive have some combination of imported fuel, expensive grid infrastructure and aggressive wildfire-hardening or storm-hardening spending. Hawaii is the extreme case because it burns imported oil for most of its electricity, which is why its rate is nearly triple the national average.

Rates are also rising fast almost everywhere: the national residential average is up about 6% year over year, and it hit an all-time high in April 2026. Data-center load growth, transmission buildout and higher natural gas prices are the usual explanations. If you are budgeting for next winter, assume your rate will be higher than the one on your last bill.

The last column prices 1,000 kWh, roughly what an average U.S. household uses in a month, so you can see what the same consumption costs in different places.

Time-of-use rates change everything

A growing share of U.S. utilities no longer charge one flat rate. Under time-of-use pricing, the same kWh costs different amounts depending on when you draw it, and the spread between peak and off-peak can be dramatic — it is common to see off-peak rates around half the flat rate and peak rates two to three times higher, with peak typically running from late afternoon into the evening on weekdays.

If you are on such a plan, the single rate this calculator takes cannot describe your bill precisely. The practical approach is to run the calculation twice: once at your off-peak rate for things you can shift, and once at your peak rate for things you cannot. A dishwasher, a clothes dryer, a pool pump and an EV charger are all easily shifted to overnight hours. Air conditioning and cooking usually are not.

The strategic point is that on a time-of-use plan, moving load is often worth more than reducing it. Shifting a dryer load from 6 p.m. to 11 p.m. can cut its cost by more than half without changing a single habit other than which button you press.

Where the savings actually are

Once you know what each appliance costs, the priority list writes itself: attack the big four, and ignore the phantom loads that get most of the attention online.

• Heating and cooling. Every degree you move the thermostat toward the outside temperature cuts HVAC energy by roughly 3%. A programmable or smart thermostat that sets back 8 degrees while you sleep and work is the highest-return $150 in the house.
• Water heating. Most electric water heaters ship set to 140°F. Dropping to 120°F cuts standby losses meaningfully and eliminates a scald risk. An insulating blanket on an older tank pays for itself in a season.
• Clothes drying. A dryer at 3,000 W is expensive per load. Running full loads, cleaning the lint filter (a clogged one adds 20–30% to run time) and using the moisture-sensor cycle instead of a fixed timer all cut real dollars.
• Refrigeration. A second beer fridge in the garage often costs $150–$250 a year to run and is usually half empty. It is the easiest single line item to delete.
• Lighting. If any incandescent or halogen bulbs remain, LEDs use about 85% less for the same light and pay back within months.
• What to skip: unplugging phone chargers and TVs. Standby draw across a whole modern home typically totals a few dollars a month. It is not where your bill is.

Frequently asked questions

Sources

• U.S. EIA — Electric Power Monthly, Table 5.6.B (residential rates)
• U.S. EIA — Electricity data
• U.S. DOE — Estimating appliance and home electronic energy use

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