These are short letter for being easy to remember:
– kWh: Kilo Watts Hour (kWh)
– A: Current (A)
– P: Power (W)
– V: Voltage (V)

For those of you out there wanting to save electricity one of the formulas you will need to know is the formula to calculate your kWh usage or electricity usage. This way you know what each device in your home is using. So you know where you can cut your costs in your home. The information found here will teach you what is a kilowatt hour, how to calculate kWh, convert watts to kWh, and more!
First of all kWh stands for Kilowatt Hours. This is usually what you will see on your electricity bill or electricity statement when you receive it. The electric company knows how much electricity you are using by reading your kWh meter. You will also have the electricity cost per kWh listed on your electric bill so you know what each kWh is costing you.

A kilowatt hour is a measurement of how many kilowatts are used in a hour. Most electrical devices will have printed on them how many watts they are using, which it takes 1000 watts to equal 1 kilowatt. So a 1000 watt microwave oven running for 1 hour will use 1 kWh.

• 1000 watts = 1 kilowatt = 1 kilowatt per 1 hour

Watts is a measurement of how much electricity that electrical device uses constantly, where kilowatt hours is how many watts that electrical device has accumulated over time.
For example a 80w incandescent light bulb in your closet will use 80 watts every time it is turned on (it shown on your electrical device), mean: 80 watts per 1 hour
But if it is turned on an hour a day while you pick out your clothes that’s 30 hours that light has been on that month. That’s 2,400 watt hours or 2.4 kilowatt hours.
But for those of you that are wanting to calculate what each electrical device in your home is using then you will need to use this formula to calculate the kWh usage in your home:

•  ( Watt Usage * Hours/Day * Days/Mo. ) / 1000 = Kilowatt Hours used that month

So for an example we have a normal iron that uses 1000w, that we have on 2 hours every day of the month. So I can calculate how many kWh this iron is using every month by using this formula:
1000w * 2 hours/day * 30.5 days/mo / 1000 = 61 kWh per month
After you know how many kilawatt hours a device is using you can multiply this kWh by the cost per kWh that is stated on your electric bill:

• kWh * Cost/kWh = Cost per month

So using the 1000w iron example, which was using 61 kWh/month.:
61 kWh * \$0.15/kWh = \$9.20/month
So a single 1000w iron will cost you \$9.20/month.

NOTE: This is based on \$0.15/kWh and also I have the amount of days per month 30.5, I figured this way I don’t have to figure out if this month is 30 days or 31 days.
You have to know how many watts a device is using before you can use any of the formulas found in the information above.
Most devices will have the wattage printed on the electrical device somewhere. If your electrical device does not have the wattage printed on it but it does have amperage printed on it, please look at Volt Amp Watt Convert and how to convert amps to watts.

How to Convert Amperage to Wattage?
So you are wanting to convert volts, amps, and watts. This is a rather simple conversion you can do with a calculator, you don’t need any special devices, but there are some devices out there that will convert volts, amps, and watts for you. Every electrical device in your home should have its voltage and amperage or voltage and watts printed on it. If not you will need to use a multimeter to find the voltage and amperage or voltage and watts.
But for those electrical devices in your home that have volts and amps or volts and watts printed you can convert amps to watts or convert watts to amps depending on what measurement you want.
If your electrical device in your home has the voltage and amperage printed on it you can convert this to watts by multiplying the voltage and amperage.

• Voltage * Amperage = Wattage

So if you have a laptop that has 19.5 volt 4.1 amp printed on the power supply then that power supply is capable of using 79.95 watts.
19.5 volts * 4.1 amps = 79.95 watts

Note: If your electrical device does not have amperage or wattage printed on it, then you will have to learn How to Measure Amperage with a Multimeter.