Backer Marathon has developed an app to assist with your engineering needs. It will help you determine wattage requirements for heating metals, liquids, and gases. You can also use it to calculate watt densities for different heater styles along with watt density guidelines. There is a temperature converter, ohms law calculator, and three phase calculator. While this app has been optimized for mobile use, it works equally well on the desktop. Use this link to access the app. https://connect.calcapp.