Compression Ratio Calculator
Calculate the Static Compression Ratio (CR) of an engine.
Distance from piston top to block deck at TDC.
Negative for dish (-5), Positive for dome (+5).
What is Compression Ratio?
Compression Ratio (CR) is the ratio of the volume of the cylinder + combustion chamber when the piston is at the bottom (BDC) versus when it is at the top (TDC).
Formula
CR = (Swept Volume + Clearance Volume) / Clearance Volume
- Swept Volume: Volume displaced by the piston stroke.
- Clearance Volume: Volume remaining at TDC (Chamber + Gasket + Deck + Piston Dish).