As you can see, the calculated cost to operate the fan with lights off is only $0.0029/hr. If you re-calculate it with the lights turned on, the cost increases by about 300% to $0.0091, but is still less than a penny per hour.alculating the cost to operate a ceiling fan is a simply a matter of knowing how many watts the fan uses and multiplying that by the cost per kWh of electricity you are being charged by your utility company. This will give you the cost per hour to run the fan.