Saving Electricity home As seen in Newsweek, Forbes, NPR, the Christian Science Monitor, CNET, PC Magazine, InfoWorld, and everywhere else. About  
Rebates & Tax Credits
for U.S. consumers

Incentives for installing insulation and for buying energy-efficient appliances like refrigerators, washing machines, and air conditioners are often available from local and state governments and utilities. You can see what's available at DSIRE,, and Energy Star.

Related sites:

Home Power Magazine. All about renewable energy for the home.

No-Impact Man. Blog about a family striving to have no net impact. (i.e., What little they use, they offset.) Inspirational.

Off-Grid. News and resources about living without being connected to a utility company.

Mr. Electricity in the news:

"Michael Bluejay runs the outstanding Saving Electricity site that I've mentioned many times before." —J.D. Roth, Get Rich Slowly

Deep Green (book) by Jenny Nazak, 2018
Small Steps, Big Strides: Building Sustainability Habits at Home (book), Lucinda F. Brown, 2016
How much money you'll save with these common energy-saving strategies, Lifehacker, Sep. 28, 2015
Radio interview about saving electricity, Newstalk 1010 (Toronto), April 21, 2015
How much does your PC cost in electricity?, PC Mech, Nov 21, 2013
How Much Electricity Do Your Gadgets Really Use?, Forbes, Sep. 7, 2013
Can my bicycle power my toaster?, Grist, June 10, 2013
Six summer debt traps and how to avoid them, Main St, June 5, 2013
To convert to gas or electric?, Marketplace Radio (NPR), July 20, 2012
8 Simple Ways to Reduce Household Waste, Living Green Magazine, June 29, 2012
Why is my electric bill so high?, New York Daily News, Mar. 27, 2012
Fight the Power, CTV (Canada's largest private broadcaster), Mar. 23, 2012
How to Cut Your Electric Bill, Business Insider, Mar. 20, 2012
Tips to save energy when using your computer, WPLG Channel 10 (Miami, FL), Feb. 23, 2012
How long will it take an energy-efficient washer/dryer to pay for itself?, Christian Science Monitor, Oct. 29, 2011
10 Easy Ways to Lower Your Electric Bill, Forbes, August 23, 2011
18 ways to save on utility bills, AARP, July 9, 2011
How to Save $500 Worth of Energy This Summer, TIME magazine, June 28, 2011
Hot over the energy bill? Turn off the A/C, just chill, Chicago Tribune, June 24, 2011
Cool Site of the Day, Kim Komando (syndicated radio host), May 29, 2011
This calculator shows how much you spend washing clothes, Lifehacker, May 6, 2011
What you pay when you're away, WCPO Channel 9 (Cincinatti), May 5, 2011
Spotting energy gluttons in your home, Chicago Tribune (CA), Apr. 7, 2011
Walnut Creek author has tips for livng a thrifty life, Contra Costa Times (CA), Jan. 24, 2011
Do space heaters save money and energy?, Mother Jones, Jan. 10, 2011
Energy steps to take for a less pricey winter, Reuters, Nov. 10, 2010
Should you shut down your computer or put it to sleep?, Mother Jones, Nov. 1, 2010
Energy saving tips for fall, Chicago Tribune & Seattle Times Nov. 7, 2010
10 ways to save money on your utility bill, Yahoo! Finance, Oct. 2, 2010
Mr. Electricity Ranks Refrigerators & Electrical Wasters, Green Building Elements, Sep. 8, 2010
The case against long-distance relationships, Slate, Sep. 3, 2010
10 household items that are bleeding you dry, Times Daily (Florence, AL), July 27, 2010
Cold, hard cash, Kansas City Star, June 22, 10
Stretch your dollar, not your budget, Globe and Mail, May 18, 2010
Auto abstinence, onearth magazine, Winter 2010
2010 Frugal Living Guide,
Energy-saving schemes yield €5.8m in savings, Times of Malta, Dec. 20, 09
Four ways to reduce your PC's carbon footprint, CNET, Dec 2, 09
The day I hit the brakes, onearth magazine, Fall 2009
How Much Do You Really Save By Air-Drying Your Clothes?, The Simple Dollar, 2010
Enjoy the mild weather, low electricity bills, Detroit Free Press, Jul 18, 09
The most energy-efficient way to heat a cup of water, Christian Science Monitor, Jun 16, 09
Ten ways to save energy, Times of Malta, Jan 3, 09
Measuring your green IT baseline, InfoWorld, Sep 4, 08
Bald Brothers Breakfast (MP3), ABC Adelaide, March 27, 2007
Net Interest, Newsweek, Feb 12, 07
The Power Hungry Digital Lifestyle, PC Magazine, Sep 4, 07
Net Interest, Newsweek, Feb 12, 07
Answers to all your electricity questions, Treehugger, Jul 11, 08 Going Green, Monsters and Critics, Jan 6, 2007
A hunt for energy hogs, Wall Street Journal Online, Dec 18, 06

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How do I measure the amount of electricity something uses?

Last Update: January 2016

Amazon pays me if you buy from stuff through my links.  At the end of the month, I pile up all the money on the bed and roll around in it.

Remember that almost every device you can plug into the wall has a label or engraving that tells you how much energy it uses. (More on figuring energy use without directly measuring it.)

But if you want to measure the energy use yourself, you can definitely do that too.

There are three ways to measure how much electricity something uses:

  1. Buy a cheap, simple watt-hour meter.
  2. Buy and install a whole-house meter.
  3. Look at the meter on the side of your house and time it.

Let's look at the first three options in turn.

(1) Buy a cheap, simple watt-hour meter

A watt-hour meter is a little device that tells you how much electricity something uses, either at a given moment or over an extended period of time. Just plug the device into the meter, plug the meter into the wall, and read the display. I like the $20 Kill-A-Watt (pictured at right).  Just plug it in and see how many watts a device is drawing at any given moment, or how many kWh you've used since you turned it on. This is especially useful for finding the amount of kWh used in a month for devices that don't run constantly, like refrigerators and window unit air conditioners.

Sadly, I can't find a plug-in meter for 220/240V appliances like ovens and clothes dryers that works in the U.S..  My understanding is that the ones the Europeans use won't work in the U.S., even with plug adapters, because the U.S. has split-phase and Europe has straight 240V.  If you need to measure 220V then you can go with a whole-house meter like the ones described next.  If you don't mind getting your hands dirty, you could also use the kind of meter that you have to run the individual black and red wires through, like the $110 EMK-25IDS.


(2) Buy & install a whole-house meter.

A whole-house meter tells you how much energy your whole house is using at any given moment, and how much you've used so far for the month—as well as how much it's costing you. These meters start at around $120 and need to be installed by an electrician. (It's an easy, 15-minute job.) Two whole-house meters you might like are The Energy Detective, and the Efergy Elite.

(3) Look at the electric meter on the side of your house.

Electric Meter Calculator
Type of meter: Kh factor: One-Reading method
Two-Reading method
Crude but fast: seconds for 1 beat

Accurate but more time-consuming: beats in seconds

Your device uses watts.   ( kWh per hour).
Clocking your electric meter is cumbersome, but it's free.
My calculator will make the job a little easier.

STEP 1:  Find the kH factor of your meter.  It's almost always printed on the meter, as in "1.0kH" or "kh7.2".   Digital meters are usually 1.0 kH and old analog meters are usually 7.2 kH.  (Some digital meters are really 1.0 kH but are mislabeled 7.2; if your calculator results with your digital meter seem 7.2x too high, type in 1.0 instead.)

STEP 2:  Decide what you're going to count.
  • The quick & dirty way is to count the number of seconds it takes for one beat of a digital meter (or one revolution of an old analog disc).  This method is easy but it's not as accurate for low-wattage devices.  If it takes at least 15 seconds for a beat, this method is fine, but if it's faster than that, use the next method.
  • The more accurate method is to count how many seconds it takes for multiple beats (e.g., 5 beats, 10 beats, your choice).  The more beats you use, the more accurate your results, but the longer it will take you to count out all those beats.
STEP 3:  Choose the "Read-Once" or "Read Twice" method:

Read-Once Method   (You have to unplug everything, but you have to read the meter only once.)

  1. Turn ON the device you want to measure, and turn OFF and unplug everything everything else, including the air conditioner, heating system, and refrigerator. (If they kick in or shut off while you're making your measurements, that will change the results.)
  2. Go outside and time your meter, as per STEP 2 above.
  3. Plug the number into my calculator.

Read-Twice Method  (You can leave most things plugged in and/or turned on, but you have to read the meter twice).

  1. Turn ON the device you want to measure, and turn OFF things that could suddenly turn on by themselves such as your refrigerator, air conditioner, or heating system.
  2. Go outside and time your meter, as per STEP 2 above.
  3. Plug the number into my calculator below. Click "Two-Reading Method" so you'll have space to enter your next result.
  4. Go inside and turn off the device you're measuring.
  5. Go outside and time your meter, as per STEP 2 above.
  6. Plug the number into the calculator.


How to count the beats on a digital meter

First we have to find out whether your meter is normal, or whether it's an exception like the GE I-210 meter, since GE thought it would be a good idea to make things difficult.

Look for three little arrows or blocks on the bottom-left or bottom-right of the display. The marks keep changing as electricity is used. Each change is a "state change". With most meters every change in the display takes the same amount of time. (In the picture at right, the marks change once per second.) So with a standard meter like this one, every state change takes exactly one "beat".

But in some meters (like the GE I-210), the changes take a differing amount of time. (e.g., the marks change steadily but then they all turn off for four-beat period of time). We'll call this a non-standard meter. The table at right shows the difference.

Beat Standard





What all this means is that you have to be sure to count the beats. With a standard meter, beats and state changes are the same thing, so it's easy. With a non-standard meter it's not. With a non-standard meter like the one in the table, it's impossible to count from beat 5 to beat 6, because you don't know when beat 7 starts. With that meter you have start to start counting on beats 1, 2, 3, 4, or 10.

An example using the calculator

Let's say you want to measure the energy used by your computer system.

STEP 1:  We have a digital meter and we found the "1.0kH" on the meter. That's the default for the calculator, so we don't have to do anything here.  If we found a different kH factor on the meter, we'd just plug that number into the calculator.  (Some digital meters are really 1.0 kH but are mislabeled 7.2; if your calculator results with your digital meter seem 7.2x too high, type in 1.0 instead.)

STEP 2:  We decided to count how many seconds it takes for 10 beats.  That'll give us pretty good accuracy.

STEP 3:  We decided to use the "Read Twice" method because we didn't want to unplug and turn off every single thing in the house.

(a) To get started, we turn our computer ON, and turn the AC and the fridge OFF.
(b) We count our electric meter.  It takes 177 seconds (nearly 3 minutes).
(c) We plug those numbers into the calculator (10 beats in 177 seconds)
(d) We turn the computer OFF.
(e) We go outside and count again.  This time it's taking a long time for each beat and we're getting impatient, so we decide to count only 3 beats.  It takes 194 seconds.
(f) We plug those numbes into the calculator (3 beats in 194 seconds), and we get the answer:  147 watts.  Ta-da!



The calculator above is all you need, but here are the formulas if you prefer to crunch the numbers yourself.

Electric Meter Formulas

Meter type

Formula type

Formula for Wattage


Crude but fast

3600 ÷ number of seconds for one beat x kH factor

Accurate but slow

3600 x number of beats ÷ number of seconds x kH factor
(measure for as many seconds as you like)


3600 ÷ number of seconds for 1 revolution x Kh factor


Many thanks to Steve, who worked in the meter shop of a utility company, for providing info for standard digital meters, and another Steve (Cook) who provided info for nonstandard digital meters.

Now that you know how to measure electric usage and you understand terms like Kilowatt, let's find out How to Save on Cooling.