Engine displacement calculator
Enter the bore and stroke of the engine and the number of cylinders. You get the total swept volume in cubic centimetres, litres and cubic inches, plus the volume per cylinder and the bore-to-stroke ratio.
Runs in your browser: nothing you enter is sent anywhere.
How to use it
- Choose metric (millimetres) or inches.
- Enter the bore and the stroke.
- Enter the number of cylinders.
- Read the displacement in cc, litres and cubic inches.
How it works
Each cylinder sweeps the volume of a cylinder of the bore’s diameter and the stroke’s height: π ÷ 4 × bore² × stroke. Multiply by the number of cylinders for the total. One litre is 1,000 cc, and one cubic inch is 16.387064 cc.
Worked example
A V8 with a 4.000 in bore and a 3.48 in stroke sweeps π ÷ 4 × 4² × 3.48 = 43.73 cu in per cylinder. Times eight that is 349.8 cu in, which is 5,733 cc or 5.73 L (the classic “350”).
Tips
- Keep bore and stroke in the same unit. Switching units with the buttons keeps each box’s own value, so check the numbers.
- Mind the cylinder count. Rotary and other non-piston engines are rated by different rules.
Frequently asked questions
How is engine displacement calculated?
Displacement = π ÷ 4 × bore² × stroke × number of cylinders. For a four-cylinder engine with an 86 mm bore and 86 mm stroke, that is about 499.6 cc per cylinder and 1,998 cc in total.
What are bore and stroke?
Bore is the diameter of the cylinder. Stroke is the distance the piston travels from the bottom to the top of its movement, which is twice the crank throw.
Why does the result differ slightly from the number on the car?
Manufacturers round displacement for the name, so a 1,998 cc engine is sold as a 2.0. Their bore and stroke figures may also be rounded, which changes the last digits.
What does the bore to stroke ratio tell me?
A ratio above 1 is called oversquare (short stroke) and tends to suit high revs. Below 1 is undersquare (long stroke). It is a design characteristic, not a quality measure.