Review: Kill-a-Watt Electricity Usage Monitor
Published on - December 4th, 2006 (Modified on - November 25th, 2007) (by J.D. Roth) 
In June I shared some tips for reducing home energy costs. Most of the information came from Michael Bluejay’s excellent guide to saving electricity. I was curious how much electricity invidual appliances use, so I ordered a gadget that Bluejay recommends: the Kill-a-Watt electricity meter. The official web site declares:
Connect your appliances into the Kill A Watt™, and assess how efficient they are. A large LCD display counts consumption by the Kilowatt-hour just like utility companies. You can figure out your electrical expenses by the hour, day, week, month, even an entire year. Monitor the quality of your power by displaying Voltage, Line Frequency, and Power Factor.
I’ve gone through our house and measured the power consumption of random devices:
- Microwave (while dormant, simply displaying time): 2 watts — It costs us roughly $2/year to leave the microwave plugged in all the time.
- Microwave (while heating a bowl of homemade bean soup for dinner): 2020 watts
- Nintendo Wii (while playing Trauma Center: Second Opinion): 16 watts — Far less power than I would have guessed.
- Strand of Christmas lights: 39 watts — More than I would have guessed. It will cost us roughly $3 to have this strand of lights plugged in during the Christmas season.
- MacBook Pro (recharging with battery at 66%): 58 watts
- Oil-filled radiator-style space heater: 520 watts on low, 820 watts on medium, and an unknown amount on high. I tripped the circuit breaker when I tried.
- Dual-control electric blanket (one side set to three, the other turned off): 80 watts, declining by a watt every few seconds (presumably because it requires less power as it gets warmer — I don’t know). I stopped watching after it had dropped to 58 watts.
- Desk Lamp: 5 watts
- Nighlight: 1 watt — Assuming the nightlight is on 12 hours/day, it costs about 50 cents to run for an entire year.
While researching this post, I learned that cable boxes are hidden power hogs. It hadn’t occurred to me to test ours, but I’ll do so tonight. (I read one report of a cable box drawing 100 watts. If you leave yours on 24/7 as we do, that’s about $100 a year!)
The Kill-a-Watt’s best feature is the ability to measure power consumption over time. If I want to see how much power the cable box really draws, for example, I can leave it plugged into the Kill-a-Watt. After a few days, I can check the cumulative power consumption in kilowatt hours and compare it to the amount of time that has elapsed. (Both of these are measured by the device.) Simple arithmetic will show me how much I’m spending to power the cable box!
The Kill-a-Watt does have some minor drawbacks:
- The unit doesn’t measure power consumption for large appliances like a range, or a washer or dryer.
- The unit itself is rather bulky. When you plug it in, it’s tall enough that it crowds (and usually blocks) the other receptacle in a standard outlet.
- The screen can be difficult to read, especially for a chubby old geek like me. The readout is relatively dim, and most outlets are located near the floor. I had to do a lot of crouching and crawling to make readings.
- The user must do some math in order to figure out overall power usage and, especially, how much the usage costs. Fortunately, the math is relatively simple.
- Once you have the initial information, the Kill-a-Watt isn’t very useful. It’s not a tool you will use all the time.
I find the Kill-a-Watt fascinating. It makes an abstract topic concrete. I can read all sorts of tips about how to save energy, but they’re all rather esoteric until I can actually see the numbers in front of me. The Kill-a-Watt gives me those numbers.
Note: I purchased this device using Amazon credit earned from this site. I also purchased several personal finance and self-development books for future review. I hope to begin “re-investing” some of the site revenue in items to review and to give away to readers.
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Just an education note for those who think the standard voltage is 110 Vac. Well on rare ocassions it may be especially in remote areas where there are long lines i.e. voltage is lower because of the resistance on the lines, but for the majority of people the EMF (electromotive force)or Voltage from your outlet is likley 115-120 VAC most of the time – (I have seen it as high as 125V)so if you measure the current consumption on the lable of the device by 110V to arrive at the power consumed most often you will get a wrong answer. The only true way is to measure both components to arrive at the true power consumption. A wattmeter does exactly this. Kill a Watt gives true consumption. By the way the lable on the device does not necessarily give the power consumption under all conditions. For example a motor under load will draw more current than no load. A cpu will draw more current when it is doing a lot of processing than if it is idle and so on.
Reducing power used even by a small amount by millions of homes is a real big deal overall.
Good to be informed so I recommend everyone know how much energy they are using and react accordingly.
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I have used even more than before… Power strips to save money. I recommend that all people do. Just flip the switch off or on when you need it. And don’t worry about the clock on the micro wave.
A penny save today can be spent tomorrow!!!
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Reply # 47 contains illogical conclusions, stating: “Upon reading the users manual for the Kill-A-Watt, it indicates that it uses 10Watts, which comes to 87.6KWH per year. At a low rate of 14-cents/KWH, that comes to 12.26/year. So, to find out that your microwave oven display clock is costing you $2/year or that your desk lamp is costing you $6 year (if left on 24/7)”
The correct conclusion is that at $.14/kwh the Kill-a-Watt will cost $12.26 a year to measure all of your equipment/appliances, not just the MW display clock and desk lamp.
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IRA, I think you missed the whole point, altogether. This is just another gadget that is being sold on the premise of saving money on energy costs. Consider the money you will spend for the device, as well as the money you are spending on energy just to operate the gadget, and you probably haven’t saved a dime.
For that matter, it doesn’t take a rocket scientist, much less a gadget, to understand that if you turn off those unnecessary lights, clocks, gadgets, computers, etc., you won’t be using as much energy. I don’t need to pay the cost of electricity to operate a gadget that is going to show me that unplugging the microwave will save me a whopping $3/year or by turning off a desk lamp might save me a whole $6/year.
So, how much are you really saving per year to run a gadget that uses electricity to tell you how much each device will save you, by turning it off? This is ludicrous.
Such things are nothing more than a waste of money, time, and plain old common sense. If you have plenty of money and no common sense, then get a hobby to take up your time. At least, you’ll probably have something more worthwhile to spend all that money on. For that matter, instead of using all that electricity to run that computer, so you can just surf the web and post illogical nonsense, just turn it off and save the energy. Of course, you won’t know how much you’re saving without a fancy gadget to help you save all that energy and money. But who cares… remember what a previous poster said, “every little bit helps”. So, how does running another gadget that uses more electricity help?
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Cranky cranky, Jim F.
I understand your point. It’s you who fails to support it with your comparison of using the meter for a full year (ludicrous) to unpluging your MW to keep the clock from using power (ludicrous) and not using your desk lamp (also ludicrous).
Around the house, initially using the meter for what adds up to a couple months is more realistic.
Examples of more realistic uses of the meter would be:
1. To find the power used by a computer system (pc, monitor, printer, scanner, UPS, etc.) when the system is in sleep/low power mode, to determine if it is worth the hastle of turn-off and reboot.
2. To find out how much power a 10 year old refrigerator is using compared to a new energy star refrigerator, to determine if it makes sense to buy the new one.
Your ranting in the last paragraph makes it hard to take your ideas seriously.
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Ira, it’s not about just a desk lamp, although your bulb may be getting a bit dim if you can’t understand the difference between literal statements and an analogy. If you need a meter to tell you that an old refrigerator is using more energy than a new one or whether you would rather pay the electric bill instead of the “hassle” to turn your computer on and off, then by all means, buy the meter and have fun with your new hobby, as you spend your time and money to find out what common sense would have told you, in the first place.
Now, your concept of a “rant” is as realistic as your understanding of an analogy. If you refuse to except the ideas, because of the way someone tries to provide an example to make their point, then it is you that can’t be taken seriously. So, as you attempt to glue your nose back on your face, don’t allow a little sarcastic wit to seem so spiteful, that you ignore the facts presented and refuse to acknowledge the validity of the information.
So, if you have an old refrigerator, check the label and it will tell you how much power it uses (keep in mind, they become less efficient with age). Then check the label on a new one and you should be able to determine if it’s worth buying the new one. Now, turn off your computer and head to the store to check those labels. YES… SERIOUSLY! Don’t waste the electricity. It doesn’t take that long to boot up.
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Jim F, assuming the refrigerator does not predate the Energy Star Labels (1992?), and that the yellow and black labels were saved, your solution is a great answer.
But if you don’t have those labels, the data tag on the refrigerator will only list maximum amps at 115VAC (or an other specified voltage). That lets us compute power used at max draw, usually when the motors start up. I wonder what the normal running power draw is? How many hours a day will the motor be running? How much power does the defrost heater draw, and for how long each day? How much energy will be saved by a new refrigerator each year? Will the purchase cost and energy saved by the new refrigerator will break even in 3, 5, 10, or 15 years?
But wait! There is a $20 meter that will answer the question in 24 hours, using less that 10 cents of electricity! And it can be used on all other appliances in the house! And my brothers house! But not your house!
You need to look up the definition of analogy. There are no analogies in either of your messages, only literal examples. Using ludicrous examples does not make them analogies.
Also look up sarcastic wit. You will find that wit requires clever use of words and ideas and a demonstration of intellect.
I’m weary of this exchange.
Goodbye
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Ira(tate)
Whether you understand the definition of anything or not, if you can’t understand that wasting money on something that common sense will answer, then by all means, buy the gadget and enjoy your new hobby in determining how many dollars you can save in a year, thereby saving the world through your “green awareness”.
If you have a pre-1992 refrigerator, I can guarantee that it is using more energy than the newer ones, today. New refrigerators today, are no less reliable than the older models, so you are not likely to have it break on you in 3 years, and in fact, your pre-92 model is much more likely to be ready for he scrap yard. DUH!
You have done nothing but try to present useless reasoning to justify your own silliness, in making yourself feel better about your efforts to be “green” and “energy efficient”. It is more likely that your only green with envy, that you didn’t realize your foolishness in purchasing a techno-geek gadget to tell you that you only need to use a little common sense to save all that money and be energy efficient through conscious thought processes which use much less energy… unless you’re just too lazy to think about it.
As for your inability to find any sarcastic wit, it is only likely to be from your lack of intellect. Of course, only coming here to attack my common sense analytics, doesn’t help to demonstrate your level of intellect. Now, go turn on your desk lamp and finish reading your dictionary, while you try to increase your literacy skills, so you can understand the technical instructions on how to properly use your new techno-gadget.
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Use common sense – just cut back on everything and save 10-25% IMMEDIATELY – nice & easy!! No need to read-up or analyze or get answers – simply just stop being pigs. We are 5 times more wasteful than the other 6.5 billion humans which our planet CANNOT sustain.
Don’t buy another big or small appliance from super polluting Asia shipped over on super toxic bunker diesel ships.
Better yet – take a wonderful trip to Paris: eat drink & be merry with wine & cheese; lose weight walking to see all the street artists, cafes, parks, museums, & galleries; and stay in a tiny tiny hotel room where you will never couch potato or worry about a big fridge/freezer. Parisians stroll daily to the “neighborhood” market and buy local fresh items.
Then come back here and free your life from your big suburban house and yard and SUV and pantry. Ignore the $10billion of advertising to buy buy buy. Forget the past and downsize 75% to an apartment in a gentrifying downtown with public parks/libraries/etc. You’ll lower paying cash to your toxic coal fired power plant electric bill 75%; lower your car costs 100% ($5000+/car/yr); lower your cleaning fixing & furnishing costs 75%; and lower your job’s income pressure 75%.
That’s right apply for a green job at 75% less wages and 75% less stress and 1000% more earth/community friendly!!
Be part of the common sense solution, not the big giant money spending too big to fail problem.
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What is the deal with Jim F?
I borrowed a Kill-a-Watt from a friend. No $20 spent on my end. I had a very high power bill and was able to identify many things that while consuming very little power in a sleep mode adds up quickly.
I am also able to identify exactly how much it does cost me to run my big screen tv, dvd, xbox, wii, playstation, AT&T uverse router, DVR, telephone, networked printer, computers, and refrigerators.
I was able to reduce my bill from 2522 KWH to 1453 KWH, and reduce my power bill about $140 for two months.
I know I use devices which require substantial power use, but adding in a few power strips that cut power when my ps, xbox, dvd, printer, and wii aren’t being used does add up.
Jim F – Why don’t you go elsewhere, where someone might value your statements, instead of acting like you are smarter than others seeking information. You only detract from the personal experiences that others may learn from.
Jonny P
Oh yeah, and your cyber-punking sucks. Grow up.
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Cyber-punking??? Uh… OK… Right.
Jonny, as I’ve stated, if you need a gadget to tell you to turn off items you aren’t using and it will save you money, then you must certainly need it. Just don’t forget to unplug the thing when you’re through with it, or you might be wasting more energy and money.
Of course, I have to remember that Pet Rocks were once a big fad and sucked a lot of money from peoples pockets, too.
Now, if you don’t find any value to my statements, then perhaps you should go elsewhere… like back to school, until you grow up. Unfortunately, common sense is not a subject that can be taught… you either have it or you don’t.
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my kill o watt meter told me what you may already know, that the biggest energy guzzlers are those that suck or blow air (dehumidifiers and vacuums), cool air (ACs) or produce heat (ovens, clothes dryers and irons).
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We performed an interesting experiment using to Kill-a-Watts to compare holiday lights. They worked great.
http://www.grimaldielectric.com/services/green-tips/97-holiday-and-christmas-lighting-led-holiday-lights-versus-traditional-holiday-lights.html
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I just measured my Wii (heh, pun intended).
It draws about 17-18 Watts while turned on at the menu (I think it was at the menu, the TV was off). About 9 Watts while off in “sleep” mode (light was yellow/orange). And only 1 Watt when it was forcefully powered down with the power button for a couple of seconds and the power light went red.
My 24 hour LED kitchen light which uses 5 LEDs only uses 6 Watts in contrast.
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Jim F (Post 47) – The Kill-a-watt meter only takes power when plugged in. If you just use it to find out how much power devices use (a few minutes to a few days per device), the electricity use is negligible. (No reason to leave it plugged in for a year, as you suggest.)
Also, using common sense in unplugging devices only works if you knows what devices use power. I found two devices (a CD player and a tape player) that used 5-6 watts each while plugged in, turned off and doing nothing. (Neither had any indicator to show they were still powered, neither has a remote to turn it on, they both have a physical on-off switch, so I was amazed to find that they were also energy vampires.)
Point is – some energy vampires are obvious, and some aren’t.
Also, about pre 1992 fridge taking large amounts of power – again, not necessarily. We have a really ancient fridge in the basement. (predates things like automatic defrost.) It is almost never opened. Turns out it takes about 183 kw-hrs/year to run it (cost about $17/year). Replacing that with a modern “energy efficient” refrigerator would not only cost hundreds of dollars for refrigerator, but probably use considerably more power because it is very difficult to find refrigerators that aren’t frost free. So again – measuring is the only way to really know what is going on.
“In theory there is no difference between theory and practice, but in practice, there is.”
(But I agree that this is a tool best borrowed, rather than bought.)
Claire F (Post 49) – the UL label isn’t the whole story. It just gives a maximum usage. Many devices vary how much they use (e.g. refrigerator or electric blanket use power to heat or cool area for a while, then they switch off for a while). To find out how much such devices really use, need to leave meter plugged in for a while. Similarly for computers, monitors, televisions, printers, dehumidifiers, etc.
Joe (post #3), and in original article:
This also explains the posts about electric blankets. The posters only checked for a short time, so they just saw the blanket heating (and no matter what it heats at the same rate). The number on the dial should control the thermostat, which tells the heater at what temperature to turn off (how long to heat, in effect). e.g., If you left the blanket on #2 all night, and measured how much power it took, and then put it on #5 and left it for the same amount of time in a room with the same ambient conditions, you should find that the higher temperature setting took more power.
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Most people do not know how much electricity they waste, how to read their electric meter, even how to read their utility bill or what it means. A kilowatt is a thousand watts PER HOUR and most people do not even know how many they use a day, month, or year. They look at their utility bill and it could be written in Greek for all they know. People leave lights on all over the house all day long, all night long. Heating water with electricity is extremely expensive compared to a solar hot water heater. You can make a solar hot water heater with an inexpensive coil of black plastic pipe.
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