Calculate your electric cost Device / Wattage (wH/hr)

---------------------- COOLING ---------------------- 3500 (2.5-ton central AC) 1440 (humongous window unit AC) 900 (medium window unit AC) 500 (tiny-ass window unit AC) 375 (central AC, fan only) 400 (evaporative cooler) 350 (central AC, fan only) 100 (floor fan or box fan) 95 (52" ceiling fan, high) 75 (48" ceiling fan, high) 55 (36" ceiling fan, high) 24 (42" ceiling fan, low) ---------------------- HEATING ---------------------- 26500 (Elec.Furnace,2000sf, cold clim.) 7941 (Elec.Furnace,1000sf, warm clim.) 1440 (Electric space heater, high) 900 (Electric space heater, medium) 600 (Electric space heater, low) 750 (Gas furnace, for the blower) 450 (Waterbed heater; avg. 10hrs/day) 425 (fan-only part of central heater) ---------------------- MAJOR APPLIANCES ---------------------- XX (clothes dryer: Choose to see note) XX (wash.machine: Choose to see note) 3800 (water heater, electric) 2000 (electric oven, 350 degrees) 1178 (elec. oven, self-cleaning, takes 4.5 hrs) 1200 (Dishwasher, drying cycle) 200 (Dishwasher, no heating or drying) 200 (Refrigerator, 22cf, avg. wattage, <1986) 72 (Refrigerator, 22cf, avg. wattage, 2001+) ---------------------- LIGHTS ---------------------- 100 (100-watt light bulb) 60 (60-watt light bulb) 25 (CFL light, 100-watt equiv.) 18 (CFL light, 60-watt equiv.) 5 (night light) 0.5 (LED night light) ---------------------- COMPUTERS ---------------------- 200 (Computer + 17" CRT) 150 (Computer + 17" LCD) 45 (laptop computer) 90 (17" CRT monitor) 40 (17" LCD monitor) 10 (Sleeping comp.+monitor) ---------------------- TV & VIDEO GAMES ---------------------- 340 (50-56" Plasma television) 260 (50-56" LCD television) 170 (50-56" DLP television) 270 (42" Plasma television) 210 (42" LCD television) 125 (32" LCD television) 75 (19" CRT television) 45 (HD Cable box) 194 (PS3) 185 (XBox 360) 70 (XBox original, not 360) 30 (PlayStation 2) 18 (Nintendo Wii) ---------------------- OTHER ---------------------- 1440 (toaster or microwave) 900 (coffee maker) 800 (range burner) 4 (clock radio) Amount used per day

1 minute/day 5 minutes/day 15 minutes/day 30 minutes/day 1 hr./day 2 hrs./day 3 hrs./day 4 hrs./day 5 hrs./day 6 hrs./day 7 hrs./day 8 hrs./day 9 hrs./day 10 hrs./day 11 hrs./day 12 hrs./day 13 hrs./day 14 hrs./day 15 hrs./day 16 hrs./day 17 hrs./day 18 hrs./day 19 hrs./day 20 hrs./day 21 hrs./day 22 hrs./day 23 hrs./day 24 hrs./day Cost of Electricity (per kWh)

CHECK YOUR OWN ELECTRIC BILL TO FIND YOUR HIGHEST kWh RATE. --------------------------- (Choose me for more on rates) --------------------------- 50¢ 40¢ 30¢ 25¢ 20¢ 16¢ 15¢ 14¢ 13¢ 12¢ 11¢ 10¢ 9¢ 8¢ 7¢ 6¢ 5¢ other... (enter your own rate...) Days used per month

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 30.4375 Kilowatt Hours used: kWh/mo. Cost per month: $ Cost per year: $ Don't misinterpret these results!

(1) Your particular computer, TV, etc. could use more or less energy than the samples listed here.

(2) Some things use more or less energy based on how high you crank them (e.g. ovens, stereos).

(3) You should generally choose highest electricity rate you're paying. See the Right and Wrong Way to Use the Calculator.

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How much electricity do household items use?

Last update: June 2013



The calculator at right will give you a rough idea of how much electricity something uses and how much it costs you. But there are some important caveats:

Electricity rates vary widely. I've found rates from 12¢ to 50¢ per kWh from the same provider. If you want results that are anywhere close to accurate, you'll need to check your own electric bill and find your actual kWh rate. Your bill might have multiple kWh rates (e.g., one for "delivery" and one for "fuel"), and in that case you should to add up them all up to get the total kWh rate. Most rates are tiered, meaning the higher your use, the higher the rate. You should generally enter your highest tier into the calculator, because any energy you save will save you money at that highest tiered rate.



Electrical use varies from model to model. I thought this would be obvious, but in hundreds of blogs and forums people say things like, "Mr. Electricity says a computer uses 150 watts," which is a mischaracterization. The calculator and table figures are just examples. (See how to misquote this website.)



Some devices use varying amounts of electricity. An easy example is an oven, whose energy use depends on how high you crank it. Perhaps a less obvious example is a washing machine, which effectively uses phenomenally more energy if you wash in hot rather than cold. Then there's the refrigerator, which alternates between periods of full energy use while the compressor is running, and then next to nothing when the compressor shuts off. (To solve this problem for fridges, the calculator lists the average wattage over time, not the higher amount used when the compressor runs.)



Most devices don't run 24/7. Therefore the "Hours per Day" and "Days per Month" fields in the calculator are crucial. Even so, you might not have a good idea about how various appliances run. So below we'll discuss which items use the most energy in a typical home. You can also measure a device's usage yourself, which gives you the best information for your own situation.







Heating 26,500 watts Elec. furnace, 2000sf, cold climate 7941 watts Elec. furnace, 1000sf, warm climate 1440 watts Electric space heater (high) 900 watts Electric space heater (medium) 600 watts Electric space heater (low) 750 watts Gas furnace (for the blower) 1100 watts Waterbed heater 450 watts Waterbed heater (avg. 10 hrs./day) Cooling 3500 watts Central Air Conditioner (2.5 tons) 1440 watts Window unit AC, huge 900 watts Window unit AC, medium 500 watts Tiny-ass window unit AC 325-425 watts Fan only for central AC (no cooling) More efficient cooling 400 watts Evaporative cooler 350 watts Whole-house fan 100 watts Floor or box fan (high speed) 90 watts 52" ceiling fan (high speed) 75 watts 48" ceiling fan (high speed) 55 watts 36" ceiling fan (high speed) 24 watts 42" ceiling fan (low speed) Major appliances 4400 watts Clothes dryer (electric) see sep. page Washing machine 3800 watts Water heater (electric) 200-700 watts Refrigerator (compressor) 57-160 watts Refrigerator (average) 3600 watts Dishwasher (washer heats water) 2000 watts Electric oven, 350°F 1178 watts Electric oven, self-cleaning mode

(takes 4.5 hrs, 5.3 kWh total) 1200 watts Dishwasher (dry cycle) 200 watts

Dishwasher (no water heating or drying)

Lighting 60 watts 60-watt light bulb (incandescent) 18 watts CFL light bulb (60-watt equivalent) 5 Night light 0.5 LED night light Computers (see more about electrical use of computers ) 150-340 watts Desktop Computer & 17" CRT monitor

1-20 watts Desktop Computer & Monitor (in sleep mode) 90 watts 17" CRT monitor 40 watts 17" LCD monitor 45 watts Laptop computer Televisions & Videogames 191-474 watts 50-56" Plasma television 210-322 watts 50-56" LCD television 150-206 watts 50-56" DLP television 188-464 watts 42" Plasma television 91-236 watts 42" LCD television 98-156 watts 32" LCD television 55-90 watts 19" CRT television 45 watts HD cable box (varies by model)

194 watts PS3 185 watts Xbox 360 70 watts Xbox 30 watts PS2 18 watts Nintendo Wii (source) Other 1440 watts Microwave oven or 4-slot Toaster 900 watts Coffee maker 800 watts Range burner 4 watts Clock radio 3 watt-hours Total energy stored by an alkaline AA battery. This is to put batteries into perspective. If you could power your clock radio with a AA battery, it wouldn't even last an hour. We have more on batteries on our Guide to Household Batteries. Wattage varies from model to model! Figures above are examples. See How to Misquote this Website.



Data for specific models of appliances is available at the Power Consumption Database.

Some devices use a little energy even when they're not on. This is called standby power, or vampire power. In most cases it's negligible, the main exception being cable TV boxes. My standby power page has more info on this.



U.S. household energy

Electrical usage of household items

At the bottom of this page is a chart showing the relative use of various appliances. (DoE) Note that this doesn't really jibe with the pie chart above from the DoE. (Refrigerators and appliances use different amounts in the different charts.) If I can ever find the time, I'll try to make my own chart.



Here are some other websites that give sample costs for various household items considering how much those items are used:

Individual Appliances



At far right is a table listing examples of the wattage of common household appliances.



Appliances that create or remove heat use the most electricity. In the table at right, appliances that make things hot are listed in red and ones that make things cold are listed in blue . As you can see, together they dwarf everything else on the list.

Don't like my table? Here's another table from Generator Sales. A database which lists power data for specific models of products is Power Consumption Database.

Remember that electrical usage varies from model to model, and that the tables on this site are just examples. (See how to misinterpret this website.)

Figuring the use of your own items



If the label gives only the number of amps and not the number of watts, then just multiply the amps by 120 to get the number of watts. (Amps x Volts = Watts, and most U.S. electricity is ~120 volts. So a hot plate rated at 6 amps uses 6 x 120 = 720 watts, on the highest setting. Most other countries use 240 volts instead of 120, so outside of North America and Japan use 240 instead of 120 in your calculations.) Note that if a device is powered by a transformer (one of those great big plugs), then the transformer has converted the electricity from AC to DC, so you need to multiply by the DC voltage, not the AC voltage of 120. For example, if the device says "INPUT 9V, 0.5A", then that's 9 volts x 0.5 amps = 4.5 watts.

You may have noticed that appliances may be labeled 110, 115, or 120 volts. U.S. appliances are actually designed to accept a range of voltages, between 110-120 volts, and the exact voltage coming out of your electrical socket can vary depending on conditions at the power plant and in your own home. Let's just agree that when we say 120 volts, we understand that it's actually a range from 110-120. And just use 120 for your calculations (unless you're outside of North America or Japan, in which case you probably have 220-240 volts).

Your device might actually list a huge voltage range, like 100-240V. That just means that it will work with any country's voltage. For your calculations, use the voltage for the country where you're plugging the device in.

Some important caveats:

The amount of electricity listed on the label is the maximum amount that the appliance will ever use. For example, a 300-watt refrigerator will only run at 300 watts when the compressor's running (which is when it makes that humming sound, indicating that it's actually chilling the air inside). Most of the time the fridge just sits there, using only 5 watts or so for its electronics. If the amount of work done by a device varies up and down, then so does its energy use. (e.g., a stereo that can be turned up or down, an oven that can be set at various temperatures, a fridge that sometimes runs and sometimes doesn't, a computer that sometimes spins its various drives and sometimes has to use more of its brainpower, etc.) The label on computers is particularly useless; a computer labeled at 300 watts probably uses only about 100. (More on computers' electrical use.) In just a bit we'll cover how to measure the actual amount of electricity being used by a device



Many consumer items are advertised according to their power output, not input. That means the stereo that says 30 watts on the box might actually require 50 watts to make 30 watts of sound (assuming the volume was cranked), and your 900-watt microwave oven might actually use 1400 watts (on its highest setting). That's because all electrical devices are inefficient -- they have to use some extra energy to do what they do.



Some devices use energy even when they're not on. (Standby power)



Exercise: Pretend there's an energy crisis and they start rationing electricity. You're given a bonus of 1000 watt-hours of electricity to use because you won a special drawing. If you're choosing between using your stereo or your central air conditioner, how long could you run each? Assume that your stereo uses 30 watts and your AC uses 3500 watts. (see answer)

1000 Wh will run a 30-watt stereo for 1000 / 30 = 33 hours. 1000 Wh will run a 3500-watt AC for 1000 / 3500 = 0.29 hours (17 minutes).

Exercise: The power adapter on your laptop computer says its output is 24V and 1.875 amps. The input specs aren't listed for some reason. What's the maximum number of watts your computer could ever use? (see answer) 24V x 1.875a = 45 watts Your adapter could draw a little more than this, because it's a little inefficient at converting the 120V to 24V, but that doesn't really matter because your computer will rarely need the full 45 watts anyway (which would require all the drives to be spinning and the processor to be fully busy).





Energy-saving strategies

Here's how much various strategies can save you.