How much electricity costs

How much electricity costs

Device wattage	Device	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	25 watts	730 hours	18 kWh

When the number is low we sometimes use watt-hours (Wh) instead of kWh. For example, we might say 240 watt-hours instead of 0.24 kWh.