What is a kiloWatt-hour a.k.a kWh? (part 1)



We have a new and improved page on "What is kWh?"

This is one of the most important articles for people just starting out understanding their electricity bill!  While I am proud of my famous What's a Watt blog, this one is just as important.

The bill you get from your power company gives you your electricity consumption in kilowatt-hours (kWh).  The price you pay for that electricity is in cents per kWh.  In Georgia, I pay around 9 cents/kWh, up North they pay round 17 cents/kWh, and in Hawaii they pay almost 30 cents/kWh! Thanks Nebraska for this handy chart.

To get your final bill amount, you simply multiply your usage (total kWh/month) times the amount you pay per kWh (your rate).  Unfortunately, you also have to pay some flat rate fees your utility charges.  Pretty simple right?

This is very obvious, but your goal is to reduce the kWh you consume each month!  So how do you achieve this?  The best targets are the big power (remember power = watt) users that are on for the longest amount of time (energy (kWh) = power (watt) * time).

When I was working at a Nuclear power plant (no, I don't glow) I remember being confused by Watts and kilo-Watt hours (I was an intern ok!) and I remember reading Michael Bluejay's great write up on the Watt/kWh .  Here is another good article from Appropedia.

I am going to go into much more detail in part 2 of What is a kWh.  I dont want to turn too many readers away at the technical stuff by writing too much at once.  It is important, so PLEASE don't blow it off.  Ignorance is not bliss when it comes to saving money and helping the environment.

Use the kilowatt hour calculator below to see how much it costs you to run an appliance.  Look at the cord or on the appliance to see how many watts the appliance uses and fill in how long you keep the appliance on per day.   If minutes, divide by 60 to get the units in hours. You'll have to know how much your utility charges you per kwh.  If you don't know your rate, you can find the average rate in your state by looking at the first image on the  Electricity Graphics page.

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Learn more about the kilo-Watt-hour in part 2!

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ckmapawatt's picture
Bryan, First, I would take out your electricity bills from last year and total up the total kWh you used for the whole year. I would then read our post on <a href="" target="_blank" rel="nofollow">solar power production by city</a> to figure out how big of a system you would need to power your home for a year. That's a very short answer to a semi-complicated question. What you should really do is speak with some solar installers in your area. Get an idea of the cost to install the system and figure out if you can afford it. If you can't afford one to power your whole home, just power part of it and then add on over time!
I just started selling Energy Electric right now and I get so many questions regardind how to read the kilowatt hours. I would like to link your site here to my webpage if that is possible. This info will help a lot of us new to this business. I am hiring more brokers and really want them to know the info.
OMG - ouch!! BUT THANKS for helping us make some progress on understanding it! You have to take this info in small increments, then step away and allow any left-eye twitches or cranial conniptions to ebb away... retain a little at a time and one day I might fully grasp this.
So how do I figure out how much i will pay if i use my 10,000w electric furnace for 2 hours a day for 30 days at .0750 per kwh?
Dear All, I think one usual mistake with the analogy to the speed comes from the way we should normally write the abbreviations and its meaning : Km/h : kilometres divided by hours ("/") kW.h : kilowatts multiplied by hours ("." usually equivalent to "x") So Km/h is a instantaneous measurement, and kW.h a totalized measurement, which confused me also at the beginning. I came across your discussion, as I am trying to understand the basic of electricity, in order to understand the solar system I have installed for my house...
I am trying to figure the daily cost of running a 1hp pool pump 12 hrs./day. The label shows 7.1/14.2 amps and 230/115 volts. Will running the pump at 230 volts use less power or simply require a smaller wire? Thanks
You are correct that operating @ 230 V would require a smaller wire but it will consume the same amount of electricity ( power equals voltage times current ).
I have two lamp 40w and 80w one panasonic fan 80w and one computer if I used 6 hours per day how many kilowatt-hour ?
That's simple. You multiply the watts by the time. ==> (40 Watt + 80 Watt + 80 Watt ) * 6 hrs = 1200 Wh = 1.2 kWh
Um... Head Hurts..


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