The data on this page represents the estimated monthly kilowatt-hour usage for many common household appliances and electrical devices. Please remember that these are only estimated averages and that exact power consumption varies based on brand, size, age and several other factors. The following data shows the appliance or device, its average wattage, its approximate frequency of use in an average household, and the estimated cost based on 13.5 cents per kWh. The cost is based on 30 days of use at the frequency indicated. To calculate kWh usage the following formula is used: (Device Wattage) multiplied by (hours used) then divided by (1000). To get the cost you then multiply $0.135 by the calculated kWh.