Engine Displacement Calculator works out the swept volume of an engine from the three numbers on its spec sheet: cylinder bore, piston stroke and cylinder count. The formula is π/4 × bore² × stroke × cylinders, and the result is shown in cubic centimetres, litres and cubic inches at once so an imperial spec and a metric one can be compared directly. Bore and stroke can be entered in millimetres or inches. The bore/stroke ratio is reported too, along with whether the engine is oversquare, square or undersquare — the shape that decides whether it makes its power high in the rev range or low down. An optional field turns combustion chamber volume into a compression ratio.
Features
Displacement in cc, litres and cubic inches from one set of inputs
Bore and stroke entered in millimetres or inches
Per-cylinder swept volume alongside the total
Bore/stroke ratio with an oversquare, square or undersquare label
Marketing-style litre badge, so 1998 cc reads as 2.0 L
Optional compression ratio from combustion chamber volume
Whole-cylinder handling — fractional counts are ignored
Everything calculated on your device
How to use the Engine Displacement Calculator
Choose whether your bore and stroke are in millimetres or inches
Enter the bore, the stroke and the number of cylinders
Read the displacement in cc, litres and cubic inches
Optionally add the combustion chamber volume to get the compression ratio
Example
Input
bore 86 mm, stroke 86 mm, 4 cylinders
Output
1998.2 cc · 2.0 L · 121.9 ci · square (ratio 1.000)
The classic 2.0 litre four — equal bore and stroke, which is why it is described as square.
Common errors & troubleshooting
The result is 1998 cc but the engine is sold as a 2.0 litre. — That is normal. Manufacturers round displacement to a marketing figure, so 1998 cc becomes 2.0 L and 5735 cc becomes a 350 cubic inch small block.
The cubic inch figure looks wrong for an imperial engine. — Make sure the unit toggle is set to inches. Entering 4.00 and 3.48 while the tool is in millimetre mode produces a tiny engine rather than a 350.
Unsure what to enter for the compression ratio field. — It wants the clearance volume — the space left above the piston at top dead centre, including the combustion chamber, head gasket and piston dish. It is usually quoted in cc on a cylinder head spec.
The cylinder count does not accept a decimal. — Cylinder counts are floored to whole numbers, since half a cylinder is not something an engine has.
Frequently asked questions
What is the engine displacement formula?
Displacement equals π divided by 4, times the bore squared, times the stroke, times the number of cylinders. The π/4 × bore² part is simply the area of the cylinder, and multiplying by stroke gives the volume one piston sweeps.
What does oversquare or undersquare mean for an engine?
Oversquare means the bore is wider than the stroke, which allows bigger valves and higher revs — typical of sports engines. Undersquare means a long stroke relative to bore, which favours low-end torque. Square means the two are equal.
How many cc are in a cubic inch?
Exactly 16.387064 cc. So a 350 cubic inch V8 is 5735 cc, or 5.7 litres, and a 2.0 litre four is about 122 cubic inches.
Does displacement alone determine how much power an engine makes?
No. Displacement sets how much air an engine can move per cycle, but forced induction, valve timing, compression ratio and the rev limit matter just as much. A 2.0 litre turbo routinely outpowers a much larger naturally aspirated engine.
Are the engine specifications I enter uploaded anywhere?
No. The bore, stroke, cylinder count and chamber volume are used only for arithmetic in your browser and are never transmitted.