This is an app for calculating electricity usage, where you can calculate electricity usage.How to use the electricity meter. Enter the energy cost you pay per kilowatt hour.Enter the number of days in the month to be calculated.Select your device. The 'Wattage (W)' field will be automatically filled in based on the device you have selected. If you are willing, you can enter your own value. This is usually printed on the nameplate of the equipment in units of watts (W) or kilowatts (kW). The listed wattage is the maximum power that the device can consume. Watts (W)=current (amperes, A) x voltage (volts, V).Enter how many devices you will be using.Enter the number of hours the device runs per day.