What in the world is a kilowatt hour?

What the heck is a kilowatt hour?

Financial costs are but one --albeit the most common-- measure of the affordability of one form of energy over another competing form of energy.

Before we see how much electricity costs, we have to understand how is electricity measured.

When you buy gas they charge you by the gallon. When you buy electricity they charge you by the kilowatt-hour (kWh).

When you use 1000 watts of electricity for a one hour duration, that's a kilowatt-hour {abbreviated as kWh}.

The average cost of electricity in terms of price charged for kilowatt hour (kWh)

Sample appliances | Mathematical formula | Electromagnetic waves | Light's cost | Confusion

For example:

Device	Wattage	Hours used	kWh
medium window-unit AC	1000 watts	one hour	1 kWh
large window-unit AC	1500 watts	one hour	1.5 kWh
small window-unit AC	500 watts	one hour	0.5 kWh
42" ceiling fan on low speed	24 watts	ten hours	0.24 kWh
light bulb	100 watts	730 hours (i.e., all month)	73 kWh
CFL light bulb (flourescent light)	25 watts	730 hours	18 kWh

Sample appliances | Mathematical formula | Electromagnetic waves | Light's cost | Confusion

To get kilowatt-hours, take the wattage of the device, multiply by the number of hours you use it, and divide by 1000.

The reason you are dividing by 1000 is because that process changes KWH from watt-hours to kilowatt-hours," according to the experts who know. That's exactly what "michaelbluejay" did in the table above.

If you'd rather not do the arithmetic then "metabolical's" handy calculator will do all the work for you. You might also be interested in my list of wattage for most household devices.

Here's the formula to figure the cost of running a device:

wattage x hours used ÷ 1000 x price per kWh = cost of electricity

The Attorney General of Massachusetts' web site says:

Kilowatt-hour (kWh): Electricity is measured in units called kilowatt-hours. One kWh is equal to 1,000 watts of power used over a period of one hour - for example, ten 100-watt light bulbs turned on for one hour. A monthly electric bill is calculated by multiplying the cost of one kilowatt-hour by the number of hours of electricity use.

Sample appliances | Mathematical formula | Electromagnetic waves | Light's cost | Confusion

Electromagnetic energy is induced from a magnetic field since light as an electromagnetic wave is a disturbance in four dimensions at once.

Sample appliances | Mathematical formula | Electromagnetic waves | Light's cost | Confusion

For example, let's say you leave a 100-watt bulb running continuously (730 hours a month), and you're paying 15¢/kWh.

Your cost to run the bulb all month is 100 x 730 ÷ 1000 x 15¢ = $10.95.

The electric utility company measures how much electricity you use in kilowatt-hours, abbreviated kWh. Your bill might have multiple charges per kWh.

• The average U.S. household uses 920 kWh a month. (Dept.. of Energy)

• American consumers in the U.S. have some of the lowest electricity rates in the world.

Most homes basically heat and cool their surroundings because they are poorly insulated, badly designed, and not oriented with respect to their local weather conditions.

My Bill:

30 kWh per day is what (900 month) I use, on average {The range is from <28 to < 41kWh / month}.

$3.42 per kilowatt-hour is what I was billed for electricity use.