How much electricity do household items use?

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:

1. 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.
   
   
2. 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.)
   
   
3. 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.)
   
   
4. 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.
   
   

5. 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
   750 watts	Central AC fan (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 power 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 not especially significant, but in some cases it can be.  My standby power page has more info.
   

Electrical usage of household items

A little farther down is a chart showing the relative use of various appliances. (DoE)  Note that this doesn't really jibe with the pie chart 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:

• University of Nebraska-Lincoln
• Seattle Light
• Cornhusker Public Power District
  
  

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 GeneratorSales.com. Databases which list power data for specific models of products include the Power Consumption Database, and the super-slow More Energy Savings.

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 only gives 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:

1. 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
   
   
2. 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.
   
   
3. 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)

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.

Easy Strategies
Strategy	Up front cost	Savings per year
(1) Use space heaters to heat only the rooms you're in, (rather than a central system that heats the whole house), and turning off the heat when you're not home.	$80	$1023
(2) Use ceiling fans instead of the air conditioner	$100 if you don't already have ceiling fans	$438
(3) Turn off lights you're not using	$0	$274
(4) Use a clothesline or a laundry rack instead of a dryer	$20	$196
(5) Sleep your computer when you're not using it	$0	$178
(6) Wash laundry in cold water instead of hot or warm	none	$152
(7) Turn off a single 100-watt light bulb, from running constantly	$0	$131
(8) Replace ten 60-watt light bulbs with compact fluorescents	$32	$123
Total	$232 once	$2515 every year
Aggressive Strategies
(9) Replace top-loading washer with front-loading washer	$500	$112
(10) Replace 1990 fridge with newer model	$300	$68
Total	$800 once	$180 every year
Assumptions: Sample electrical rate of 15¢/kWh. (1) One 5000-watt central system, always on, running 40mins/hr. for four months, vs. two 1500-watt heaters running 8 hours a day for four months. (2) A 2.5-ton, 3500-watt AC 24 hours a day (15 mins/hr) for five months, vs. two 48" ceiling fans on high (75 watts each), 12 hours/day. (3) Five 100-watt light bulbs on for 10 hours a day when they don't need to be. (4) 50¢/load as per the clothes dryers page, 7.5 loads a week. (5) Computer on for 24 hrs/day @ 160 watts, vs. sleeping 21 hrs/day @ 5 watts (6) Electric water heater; 7.5 loads/week. (8) CFL's are 15 watts, lights run 5.5 hours a day. (9) 1/3 hot washes, 2/3 warm washes, water heated electrically, electric dryer, 7.5 loads/week. Includes water costs. (10) Replacing a 900 kWh/year top-freezer model with a 450 kWh/year top-freezer model

 

» Now see how to measure electrical use »

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