Free Engine Displacement calculator with clear step-by-step results.
Displacement is the swept volume of one cylinder multiplied by cylinder count, where swept volume is the bore's circular area times the stroke. The bore-to-stroke ratio is the other number worth knowing: above 1.0 is oversquare and revs freely, below 1.0 is undersquare and favours low-end torque.
Swept volume per cylinder
cc = pi x (bore mm / 20)^2 x (stroke mm / 10)
Total displacement
Total cc = swept volume per cylinder x number of cylinders
It converts millimetres to centimetres and halves the bore to get the radius in one step, so the result comes out directly in cubic centimetres.
It sets the air the engine can breathe per cycle, but boost, compression, valve timing and rev limit matter just as much. A 2.0 litre turbo routinely outproduces a 3.0 litre naturally aspirated engine.