Engine Displacement Calculator
Engine capacity from bore, stroke and cylinder count — plus the bore-to-stroke ratio that shapes its character.
Displacement is the swept volume of one cylinder times the number of cylinders: the bore area multiplied by the stroke.
How the engine displacement calculator works
Displacement is the swept volume of one cylinder times the number of cylinders: the bore area multiplied by the stroke.
The bore-to-stroke ratio tells you more than the capacity does. An oversquare engine, bore wider than stroke, has lower piston speeds at a given rpm and revs higher — the classic sports-car layout. An undersquare or long-stroke engine makes torque lower down and is what most diesels and older engines use. A ratio near 1.0 is square.
Compression ratio is a separate figure this also computes, from the combustion chamber volume you supply.
Formula: displacement = π/4 × bore² × stroke × cylinders
Worked examples
| Inputs | Displacement | Note |
|---|---|---|
| A square 2.0-litre four | 1998.2 cc (2 litres) | 1,998 cc |
| A long-stroke diesel | 1991.1 cc (1.99 litres) | undersquare |
| A big V8 | 6162.4 cc (6.16 litres) | about 6.2 litres |
FAQFrequently asked questions
How is engine displacement calculated?
Bore area times stroke gives one cylinder's swept volume; multiply by the number of cylinders.
What is bore-to-stroke ratio?
Bore divided by stroke. Above 1 is oversquare and revs freely; below 1 is long-stroke and makes torque lower down.
Why do diesels have long strokes?
A longer stroke gives more leverage on the crankshaft, which suits the high torque and low rpm diesels are designed for.
What is compression ratio?
Swept volume plus chamber volume, divided by chamber volume. Petrol engines run around 10:1 to 13:1; diesels 15:1 and above.
Does bigger displacement mean more power?
It helps, but forced induction changes everything — a turbocharged 2.0 litre routinely outpowers an older naturally aspirated 3.0.
Where these figures come from
- ISO 4000 / ETRTO — tyre designation and dimensions — the width / aspect ratio / rim marking this page decodes
- UK Vehicle Certification Agency — the official UK fuel and emissions data
Last checked: September 2026. Tyre dimensions follow the ISO metric marking standard; engine formulas are the standard textbook forms.