Engine Displacement Calculator
Calculate engine displacement in cubic centimetres (cc) and litres from bore, stroke, and cylinder count.
Reviewed by the ToolNestr Editorial Team — July 2026
How engine displacement is calculated
Engine displacement is the total swept volume of all pistons inside the cylinders. It is one of the most fundamental specifications of an internal combustion engine and is calculated using basic geometry. Each cylinder is essentially a tube, and the volume it displaces is the area of the circular cross-section (bore) multiplied by the length the piston travels (stroke). Multiply by the number of cylinders to get the total engine displacement.
The formula uses the bore diameter, stroke length, and cylinder count. The bore is halved to get the radius, squared, multiplied by pi for the area, then by the stroke for the single-cylinder volume, and finally by the number of cylinders. Inputs can be in millimetres or inches, with the result converted to both cubic centimetres (cc) and litres.
The formula explained
Worked example
Bore: 86 mm · Stroke: 86 mm · Cylinders: 4
Engine Building
Calculate the displacement of a custom-built engine from your bore and stroke specs before machining begins.
Racing Class Compliance
Many racing series have strict displacement limits. Verify your engine build falls within the class regulations.
Engine Identification
Identify an unknown engine by measuring its bore and stroke and calculating displacement to match against known engine families.
Performance Tuning
Oversize pistons and stroker cranks increase displacement. Calculate the exact cc gain before investing in performance parts.
How to use the engine displacement calculator
Enter bore and stroke
Type the cylinder bore diameter and piston stroke length. Most modern engines use millimetres.
Select cylinder count
Choose the number of cylinders from 1 to 16. Common configurations are 4, 6, and 8.
Read both units
Displacement shown in cc (cubic centimetres) and L (litres) simultaneously.
Tips for displacement calculations
Bore and stroke are usually in mm
Most modern engine specs use millimetres. If you have inches (common for older American V8s), switch the unit selector.
Oversize pistons increase displacement
A typical engine rebore adds 0.5–1.0 mm to the bore diameter. Recalculate with the new bore to see your exact post-rebuild displacement.
Displacement vs power
Displacement is only one factor in power output. Forced induction (turbo/supercharger), compression ratio, and valve timing all significantly affect horsepower.
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Frequently asked questions
What is engine displacement?
Displacement is the total volume swept by all pistons from top dead centre to bottom dead centre. It is a key indicator of engine size and power potential.
What is bore and stroke?
Bore is the diameter of each cylinder. Stroke is the distance the piston travels up and down inside the cylinder.
Which units can I use?
Bore and stroke can be entered in millimetres (most common) or inches. Results are shown in cc and litres.
How do I measure bore and stroke?
Bore is measured with an inside micrometer across the cylinder wall. Stroke is measured from crankshaft specs or with a dial indicator.
What is engine displacement used for?
Displacement determines engine class for racing, insurance groups, tax bands, and is a rough indicator of power and torque potential.
Sources & references
This tool uses standard formulas and reference values from:
- • SAE International standards (e.g. J1349 engine power, J1634 EV range). sae.org
- • U.S. DOE / EPA — fueleconomy.gov, official efficiency, MPGe and charging figures. fueleconomy.gov
- • Vehicle manufacturer service specifications — always defer to the OEM figures for your specific vehicle.
General estimates. Follow your manufacturer’s published specifications and a qualified mechanic for safety-critical work.