How displacement is calculated
Each cylinder sweeps a cylinder-shaped volume as the piston travels the length of the stroke. Multiply that by the number of cylinders:
displacement = π/4 × bore² × stroke × cylinders
With bore and stroke in millimetres the result comes out in cubic millimetres, so we divide by 1000 for cc, by 1,000,000 for litres, and by 16.387 for cubic inches. A bigger bore raises displacement with the square of the diameter, which is why even a small overbore adds up; a longer stroke adds it linearly and also changes the engine's character.
FAQ
Why doesn't my result match the badge exactly?
Manufacturers round. A "2.0" is rarely exactly 2000 cc — it might be 1984 or 1998. Enter the real bore and stroke and you'll see the true swept volume; the badge is just the nearest tidy number.
Bore and stroke in inches?
This calculator takes millimetres. To convert, multiply inches by 25.4. The cubic-inch output is there so you can cross-check against US engine specs.