kilowatt-hours

How much electricity do different devices actually use? This is measured in units called kilowatt-hours. How many kilowatt-hours a device uses depends on a) its power and b) how long it is used for.

If we use a device which has a power of 1 kilowatt for 1 hour then we say that it has used 1 kilowatt-hour of electricity

Number of kilowatt-hours (kWh)     =       Power (kW)     x     hours (h)

a 3kW vacuum cleaner for 1 hour	a 2kW kettle for 1/2 an hour	a 500W television for 6 hours	a 1.2kW drill for 20 minutes
3 x 1 = 3kWh	2 x 0.5 = 1kWh	0.5 x 6 = 3kWh	1.2 x 0.33 = 0.8kWh

remember 1000W = 1kW, so 500W would be 0.5kW. Also, if you are given the time in minutes you will need to change it to hours.