Engine Displacement Calculator

Engine displacement, the figure quoted whenever an engine is described as a 2.0 litre or a 5.0 litre, is the total volume swept by all of its pistons as they move through their cylinders, and this calculator works it out from the three numbers that define it: the bore, the stroke and the number of cylinders. The bore is the diameter of each cylinder, the stroke is how far the piston travels from the bottom of the cylinder to the top, and multiplying the circular area of the bore by the stroke gives the swept volume of one cylinder. Multiply that by the number of cylinders and you have the engine's displacement. Enter the bore and stroke in millimetres along with the cylinder count, and the calculator returns the displacement in both cubic centimetres, the precise engineering figure, and litres, the rounded headline number, as well as the swept volume of a single cylinder. Displacement is one of the most fundamental measures of an engine, because, broadly speaking, a larger swept volume can take in more air and fuel and therefore produce more power and torque, which is why it features so prominently on spec sheets, in vehicle registration, and in motorsport class rules. It also feeds directly into other engine calculations such as the compression ratio and volumetric efficiency. This makes the tool genuinely useful for mechanics, engine builders and rebuilders working out the capacity of a modified or bored-out engine, for enthusiasts checking a specification, and for students learning how bore and stroke combine to set engine size. Because it recalculates as you type, you can see how over-boring a cylinder or changing the stroke alters the total capacity. The formula and a worked example are explained clearly below.

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