How Much Does It Cost to Run an Appliance? Watts × Hours × Rate

By Sam Whitaker · Updated 2026-09-28

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To find what an appliance costs to run, multiply its watts by the hours it runs, divide by 1,000 to get kilowatt-hours (kWh), and multiply by your price per kWh. At the U.S. average residential price of 18.31¢ per kWh for July 2026 (EIA), a 1,500-watt space heater used 4 hours a day for 30 days uses 180 kWh and costs $32.96. The same use costs $22.90 in Louisiana, the lowest state average that month at 12.72¢, and $86.40 in Hawaii, the highest at 48.00¢.

Appliance	DOE nameplate range (W)	Watts used	Example hours/day	kWh per 30 days	U.S. average, 18.31¢	Louisiana, 12.72¢	Hawaii, 48.00¢
Dehumidifier	785	785	8	188.4	$34.50	$23.96	$90.43
Portable space heater	750–1,500	1,500	4	180.0	$32.96	$22.90	$86.40
Clothes dryer	1,800–5,000	5,000	1	150.0	$27.47	$19.08	$72.00
Whole-house fan	240–750	750	4	90.0	$16.48	$11.45	$43.20
Dishwasher	1,200–2,400	2,400	1	72.0	$13.18	$9.16	$34.56
Window fan	55–250	250	8	60.0	$10.99	$7.63	$28.80
Ceiling fan	65–175	175	8	42.0	$7.69	$5.34	$20.16
Clothes washer	350–500	500	1	15.0	$2.75	$1.91	$7.20
Flat-screen TV	120	120	4	14.4	$2.64	$1.83	$6.91
Hair dryer	1,200–1,875	1,875	0.25	14.06	$2.57	$1.79	$6.75
Clothes iron	1,000–1,800	1,800	0.25	13.5	$2.47	$1.72	$6.48
Laptop computer	50	50	8	12.0	$2.20	$1.53	$5.76
Vacuum cleaner	1,000–1,440	1,440	0.25	10.8	$1.98	$1.37	$5.18
Coffee maker	900–1,200	1,200	0.25	9.0	$1.65	$1.14	$4.32
Microwave oven	750–1,100	1,100	0.25	8.25	$1.51	$1.05	$3.96
Toaster	800–1,400	1,400	0.1	4.2	$0.77	$0.53	$2.02
Refrigerator (frost-free, 16 cu ft)	725	n/a	n/a	n/a	n/a	n/a	n/a
Water heater (40 gallon)	4,500–5,500	n/a	n/a	n/a	n/a	n/a	n/a

Every cost in the table is watts × example hours per day × 30 days ÷ 1,000 × the price per kWh, rounded to the cent. The two n/a rows are appliances that cycle on and off, where nameplate watts × hours does not describe real use; the EnergyGuide sections below cover them.

Where the wattages, hours and prices come from

Wattages: the nameplate wattage list in DOE’s Energy Saver guide to estimating appliance energy use, from an archived copy captured February 18, 2013; the live DOE page returned “Page not found” when checked in September 2026. DOE describes the nameplate figure as the maximum power an appliance draws, so the table uses the top of each range, and a model at the bottom of a range costs proportionally less. The list is more than a decade old, so a newer model may draw less than shown; the nameplate or EnergyGuide label on your own model is the better input.
Hours: examples for illustration, not measured averages. Cost scales directly with hours, so replace them with your own.
Prices: EIA Electric Power Monthly Table 5.6.A, residential sector, July 2026: U.S. 18.31¢, lowest state Louisiana 12.72¢, highest state Hawaii 48.00¢ per kWh. EIA labels the values preliminary estimates.
EnergyGuide appliances: according to the FTC, dishwashers, clothes washers and televisions also carry EnergyGuide labels, so for those rows the label’s kWh per year is a better number than nameplate watts.

DOE also notes that a dishwasher’s drying feature greatly increases its energy use. An electric dryer’s 5,000 W is likewise a nameplate maximum, not a constant draw. A dehumidifier switches on and off with its humidity setting and is not on the FTC’s EnergyGuide list, so its 8 example hours stand for hours of actual running; a plug-in meter measures that directly.

Example: 1,500-watt space heater, 4 hours a day

Example, using the top of DOE’s 750–1,500 W range for portable heaters:

Daily energy: 1,500 W × 4 hours ÷ 1,000 = 6 kWh
30 days: 6 kWh × 30 = 180 kWh
Cost: 180 kWh × $0.1831 = $32.96 at the U.S. average; 180 × $0.1272 = $22.90 in Louisiana; 180 × $0.4800 = $86.40 in Hawaii

On a 750 W setting, the same hours use 90 kWh, or $16.48 at the U.S. average (90 × $0.1831). A heater with a thermostat may cycle off once the room warms, so 4 hours switched on can mean fewer hours at full wattage; a plug-in meter, covered below, shows the kWh actually used.

Why cycling appliances need the EnergyGuide number

Refrigerators, air conditioner compressors and water heaters switch on and off to hold a temperature, so multiplying their nameplate watts by the hours they are plugged in overstates what they use. DOE notes that a refrigerator, though always “on,” cycles as needed to keep its interior at temperature. ENERGY STAR describes a conventional room air conditioner’s compressor as running at full capacity when the thermostat calls for cooling and switching off once the set temperature is reached; variable-speed models adjust compressor speed instead.

For these appliances, use the kWh per year printed on the yellow EnergyGuide label. The FTC lists the products that carry it: refrigerators, freezers, water heaters, room and portable air conditioners, central air conditioners, heat pumps, furnaces, boilers, pool heaters, clothes washers, dishwashers, televisions and ceiling fans. The FTC also notes that the label’s dollar figure is an estimate based on typical use and a national average energy price, so recompute the cost with your own price:

Cost per year = label kWh per year × your price per kWh

Example: refrigerator from its EnergyGuide kWh per year

Example: ENERGY STAR’s certified refrigerator data (retrieved September 2026) lists a 17.6 cu ft top-freezer model with automatic defrost and no ice maker at 360 kWh per year; the U.S. federal standard for that model is 376 kWh per year. Treating 360 kWh as the label value:

Per 30 days: 360 kWh ÷ 365 × 30 = 29.59 kWh
Cost per 30 days: 29.59 × $0.1831 = $5.42 (U.S.); 29.59 × $0.1272 = $3.76 (Louisiana); 29.59 × $0.4800 = $14.20 (Hawaii)
Cost per year: 360 × $0.1831 = $65.92 (U.S.); 360 × $0.1272 = $45.79 (Louisiana); 360 × $0.4800 = $172.80 (Hawaii)

Compare DOE’s older rule of thumb, which divides plugged-in time by three to estimate hours at full wattage: 725 W (DOE’s figure for a 16 cu ft frost-free refrigerator) × 8 hours ÷ 1,000 = 5.8 kWh a day, or 2,117 kWh a year. That is almost six times the label figure for the newer model, which is why the label number, or a meter reading, is the one to use.

Example: 8,000 Btu/h window air conditioner

Example: ENERGY STAR’s certified room air conditioner data (retrieved September 2026) includes 8,000 Btu/h window units with a combined energy efficiency ratio (CEER) of 15, rated at 400 kWh per year. DOE’s room air conditioner test procedure counts 750 hours of cooling a year when it calculates annual energy use.

Energy per cooling hour: 400 kWh ÷ 750 hours = 0.533 kWh, an average draw of about 533 W (the same as 8,000 Btu/h ÷ 15 Btu per watt-hour). CEER also counts standby and off-mode energy, so this is slightly above the cooling-only draw.
8 hours of compressor run time a day for 30 days is 240 hours: 400 kWh × 240 ÷ 750 = 128 kWh
Cost: 128 × $0.1831 = $23.44 (U.S.); 128 × $0.1272 = $16.28 (Louisiana); 128 × $0.4800 = $61.44 (Hawaii)

The full rated 750-hour cooling year costs 400 × $0.1831 = $73.24 at the U.S. average. The hours to count are the hours the compressor runs, not the hours the unit is switched on.

Standby power while switched off

DOE notes that many appliances keep drawing a small amount of standby power when switched off, including TVs, stereos, computers and kitchen appliances, and that unplugging them or switching off a power strip cuts that load. The formula is the same, with 24 hours a day.

Example: a device that draws 5 W on standby around the clock: 5 W × 24 hours × 30 days ÷ 1,000 = 3.6 kWh, or $0.66 per 30 days at the U.S. average (3.6 × $0.1831). Measure the actual standby watts with a plug-in meter rather than assuming a figure.

Measuring real use with a plug-in meter

DOE’s guidance on plug-in electricity usage monitors:

They measure devices that plug into 120-volt outlets, not 240-volt appliances such as electric clothes dryers, central air conditioners or water heaters.
Plug the monitor into the outlet and the device into the monitor; the display shows the watts the device draws.
Leave it connected for a day or longer to read accumulated kWh, which captures the on-off cycling of devices such as refrigerators.
Some monitors accept your price per kWh and show the running cost.

For 240-volt appliances, DOE points to whole-house energy monitoring systems, which are often installed in the main breaker panel and may require an electrician.

Example: a meter on a refrigerator reads 2.4 kWh after 48 hours: 2.4 ÷ 2 = 1.2 kWh a day; 1.2 × 30 = 36 kWh; 36 × $0.1831 = $6.59 per 30 days.

When the label lists amps instead of watts

If an appliance lists only amperes, DOE’s method is watts = amps × volts. Most U.S. appliances use 120 volts; larger ones such as clothes dryers and electric cooktops use 240 volts.

Example: a paper shredder rated at 3 amps: 3 A × 120 V = 360 W. Used 15 minutes a day for 30 days: 360 × 0.25 × 30 ÷ 1,000 = 2.7 kWh; 2.7 × $0.1831 = $0.49.

Which electricity price to use

EIA’s state figures are average revenue per kWh: residential electricity revenue divided by kWh sold, covering generation, transmission, distribution, taxes and fees. EIA notes that these averages are not utility rates, and that rates can depend on the type of customer, how much electricity is used and, sometimes, when it is used. The July 2026 U.S. residential average of 18.31¢ compares with 17.45¢ for July 2025 in the same table.

For the closest estimate, use the per-kWh price on your own bill. State averages are in electricity rates by state, typical monthly totals are in average electric bill by state, and EV charging, which uses the same kWh × price math, is covered in cost to charge an EV at home by state.

These are general-information estimates, not professional advice.

Sources

Figures on this page are general-information estimates, not professional advice. Check the stated assumptions and any linked manufacturer or primary sources before buying materials.