Fitting a new motor, swapping an electric drive for a petrol engine, or building a compressor from parts? The calculator estimates the shaft power a multi-stage breathing-air compressor needs for its delivery and final pressure, the current an electric motor draws on single- or three-phase supply, and the pulley size that brings the block to its design speed.
The work of each stage comes from the real-gas properties of air, and the default efficiency is set against the motors the makers actually fit.