Softonic

Engine Displacement Calculator

Step 1 / 3 Displacement (cc)
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Work out an engine’s displacement from three numbers: cylinder bore, piston stroke and the number of cylinders. Enter the bore and stroke in millimetres and the calculator returns the swept volume per cylinder, the total displacement in cubic centimetres (cc), the equivalent in liters and the figure in cubic inches (CID). It is handy for car and motorcycle builds, comparing engines across spec sheets, sizing rebore work, or simply understanding what “2.0L” or “1340cc” really means.

How to use the engine displacement calculator

  1. 1

    Enter bore and stroke

    Type the cylinder bore and the piston stroke, both in millimetres.

  2. 2

    Add the cylinder count

    Enter how many cylinders the engine has (4, 6, 8 and so on).

  3. 3

    Read the displacement

    See total displacement in cc, liters and cubic inches, plus the per-cylinder volume.

The engine displacement formula

Displacement is the total volume swept by every piston as it moves from bottom to top. For one cylinder it is the volume of a cylinder of diameter equal to the bore and height equal to the stroke:

per-cylinder volume (cc) = (π ÷ 4) × bore² × stroke ÷ 1000
total displacement (cc)  = per-cylinder volume × number of cylinders

Bore and stroke are in millimetres, so dividing by 1000 converts cubic millimetres to cubic centimetres (cc). To convert further:

liters       = total cc ÷ 1000
cubic inches = total cc ÷ 16.387

Worked example

Take a “square” four-cylinder engine with an 86 mm bore and an 86 mm stroke:

  • Per cylinder = (π ÷ 4) × 86² × 86 ÷ 1000 ≈ 499.6 cc
  • Total = 499.6 × 4 ≈ 1,998 cc → about 2.0 L
  • In cubic inches = 1,998 ÷ 16.387 ≈ 121.9 CID

That is why a 2.0-litre four is so common: an 86 × 86 mm bore-and-stroke lands almost exactly on 2,000 cc.

Bore, stroke and engine character

Layout Bore (mm) Stroke (mm) Cylinders Displacement
Square 86 86 4 ≈ 1,998 cc
Undersquare 84 90 4 ≈ 1,995 cc
V8 101.6 92 8 ≈ 5,967 cc
Big twin 103.5 111.1 2 ≈ 1,870 cc

An oversquare (bore larger than stroke) engine tends to rev higher; an undersquare (long-stroke) engine favours low-end torque.

Common pitfalls

  • Mixing units. Bore and stroke must both be in millimetres here. A bore quoted in inches must be converted first (1 in = 25.4 mm).
  • Confusing bore with radius. The formula uses the full bore (diameter), not the radius.
  • Rounding too early. Round only the final cc/L/CID figures, not the intermediate per-cylinder value.

Frequently Asked Questions

Displacement is the combined volume swept by all the pistons in one full stroke. It is the headline “size” of an engine, quoted in cc, liters or cubic inches, and is a rough guide to its air-handling capacity and power potential.

Divide cubic centimetres by 1000 to get liters (2,000 cc = 2.0 L). Divide cc by 16.387 to get cubic inches (2,000 cc ≈ 122 CID). The calculator shows all three at once.

Bore is the diameter of the cylinder; stroke is the distance the piston travels from bottom to top. A larger bore relative to stroke (oversquare) suits high revs, while a longer stroke favours low-end torque.

No. Nothing you enter is stored, saved or shared. The bore, stroke and cylinder values are sent to our server only to run the calculation and are not kept afterwards. In the multi-step view, the values are also carried in the page link.

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