There are two ways of calculating the compression ratio for an engine. The compression ratio is the ratio between two elements: the gas volume in the cylinder with the piston at its highest point (top dead center of the stroke, TDC), and the gas volume with the piston at its lowest point (bottom dead center of the stroke, BDC). The compression ratio of an engine is a very important element in engine performance.
How to use this calculator: Simply fill in all the boxes below with the requested figures and click on 'Calculate CR' to find your engine's compression ratio. This compression ratio calculator can be used to work out the compression ratio of your engine.
