Displacement is the total volume the pistons sweep — the headline size of an engine.
Where
| Bore | Cylinder diameter |
| Stroke | Distance the piston travels |
| Cylinders | Number of cylinders |
Worked example
A 3.5 in bore, 3.0 in stroke, 6-cylinder engine: 0.7854 × 3.5² × 3.0 × 6 = 173 in³, about 2.8 L.
FAQ
Why does displacement matter beyond just engine size bragging rights? Displacement roughly correlates with an engine’s air intake capacity per cycle, which relates to potential power output, though modern factors like turbocharging, valve timing, and compression ratio mean displacement alone doesn’t determine actual horsepower.
Does cylinder count affect the displacement formula? Total displacement is the sum of all cylinders’ swept volume, so for a fixed total displacement, more cylinders means each individual cylinder is smaller, which affects characteristics like smoothness and rev range more than total output.
Use the Engine Displacement calculator in the automotive calculators.