If you'd like to know your estimated Power Perfect Box savings then use the calculator below to estimate your savings. You will first enter your Kilowatt Hour months total of the previous years comparing month. Next enter your cost per kWh. In the next bracket you will insert the number of kWh used in the comparing month and again you will insert the cost per kWh in the next bracket. Below that you will see your kWh savings percentage and followed by your dollar amount savings percentage.