What Is Engine Displacement?

Engine displacement is the total volume swept by all the pistons inside an engine's cylinders in a single movement from the top to the bottom of their stroke. It is a fundamental measure of an engine's "size" and is commonly expressed in Cubic Inches (CID), Liters (L), or Cubic Centimeters (CC).

Generally, a larger displacement engine has the potential to produce more power and torque than a smaller one because it can combust a larger volume of air-fuel mixture per revolution. However, factors like turbocharging, supercharging, and engine design can allow smaller engines to be very powerful.

Key Terminology Explained

• Bore: The diameter of the engine's cylinder.
• Stroke: The distance the piston travels within the cylinder from its highest point (Top Dead Center) to its lowest point (Bottom Dead Center).

How is Engine Displacement Calculated?

The calculation first finds the volume of a single cylinder and then multiplies it by the number of cylinders. The formula for the volume of a cylinder is:

Volume = π × (Bore / 2)² × Stroke

Our calculator performs this calculation and then converts the final result into the three most common units of measurement.

Displacement, Torque, and Horsepower

Engine displacement is the foundation upon which power is built. The volume of air and fuel an engine can draw in (its displacement) directly influences its potential to create torque (rotational force). This torque, when multiplied by engine speed (RPM), determines the final horsepower output.

To see how torque and RPM translate into power, or to estimate your vehicle's power from its performance, check out our Engine Horsepower Calculator. Understanding these interconnected concepts provides a complete picture of your engine's performance characteristics.

"Square," "Undersquare," and "Oversquare" Engines

• An oversquare (or short-stroke) engine has a bore larger than its stroke. These engines can typically achieve higher RPMs safely, making them common in high-performance sports cars.
• An undersquare (or long-stroke) engine has a stroke longer than its bore. These designs tend to produce excellent low-end torque, making them suitable for trucks and cruisers.
• A square engine has a bore and stroke that are equal or very close in measurement, providing a balance between torque and high-RPM power.