Enter the bore diameter and stroke length into the calculator to determine the engine displacement.

Bore X Stroke Formula

The following formula is used to calculate the engine displacement using bore and stroke measurements.

ED = π/4 * D^2 * S * N


  • ED is the engine displacement (cc) D is the bore diameter (mm) S is the stroke length (mm) N is the number of cylinders

To calculate the engine displacement, first square the bore diameter. Then multiply this result by the stroke length. Multiply this result by the number of cylinders. Finally, divide this result by 4 and multiply by pi (approximately 3.14159).

What is a Bore X Stroke?

Bore X Stroke refers to the diameter of the cylinder in an engine (bore) and the distance the piston travels within the cylinder (stroke). These two measurements determine the engine’s total displacement, or the total volume of air/fuel mixture an engine can draw in during one complete engine cycle. In general, a larger bore and stroke equates to a larger displacement, which can produce more power. However, the ratio between the bore and stroke also affects the engine’s efficiency and power characteristics.

How to Calculate Bore X Stroke?

The following steps outline how to calculate the Bore X Stroke using the given formula:

  1. First, determine the bore diameter (D) in millimeters (mm).
  2. Next, determine the stroke length (S) in millimeters (mm).
  3. Next, determine the number of cylinders (N).
  4. Next, square the bore diameter (D^2).
  5. Next, multiply the squared bore diameter (D^2) by the stroke length (S).
  6. Finally, multiply the result by π/4 to calculate the engine displacement (ED) in cubic centimeters (cc).

Example Problem:

Use the following variables as an example problem to test your knowledge:

bore diameter (D) = 80 mm

stroke length (S) = 75 mm

number of cylinders (N) = 4