Calculated Industries’ Sheet Metal/HVAC Pro Calc is an advanced construction-math calculator and app designed specifically for sheet metal and HVAC trades. The calculator is available as both a hand-held calculator and as an app for iPhone and Android mobile devices. It comes with numerous built-in functions, including the fan law functions to simplify test and balance, velocity and velocity pressure. Some of its sheet metal functions include x, y, r (radius), theta and seg radius. This calculator also converts between polar and rectangular coordinates.