Engine Displacement Calculator

Bore is the diameter of each cylinder; stroke is how far the piston travels up and down inside it. The volume a single piston sweeps — its swept displacement — is the circular area of the bore multiplied by the stroke. Multiply by the number of cylinders for the engine’s total displacement.

Worked example: an 86 mm bore, 86 mm stroke and four cylinders gives (π ÷ 4) × 86² × 86 × 4 ÷ 1,000 = 1,998.2 cc (about 2.0 litres, or 121.9 ci).

Displacement describes the swept volume of the cylinders — nothing more. It does not determine horsepower, torque, compression ratio, or how an engine performs. Two engines of identical displacement can produce very different power depending on turbocharging, valve timing, compression and tuning.

This calculation also ignores combustion-chamber volume, so it is not the engine’s total cylinder volume, and it cannot be used to infer compression ratio.