Engine Displacement Calculator
Calculate engine displacement in cubic centimeters (cc) and liters from bore, stroke, and number of cylinders.
How to use this tool
- Enter the cylinder bore diameter in millimeters.
- Enter the piston stroke length in millimeters.
- Enter the number of cylinders.
- The calculator returns displacement in cc and liters.
Compute exact engine displacement from bore, stroke, and cylinder count.
⚠ This tool provides general estimates for education only and is not financial, tax or legal advice. Figures may not reflect your situation — verify with a qualified professional.
Formula
Swept volume per cylinder (cc) = (π ÷ 4) × bore2 × stroke ÷ 1000
Total displacement (cc) = swept volume per cylinder × number of cylinders
Displacement (L) = displacement (cc) ÷ 1000
All bore and stroke values are in millimeters.
How it works
Engine displacement is the total swept volume traced by all pistons in one full stroke cycle, calculated from the cylinder bore diameter, the piston stroke length, and the number of cylinders. The formula treats each cylinder as a perfect right circular cylinder, so bore roundness and chamfer tolerances are not accounted for. Results closely match manufacturer specifications when factory bore and stroke dimensions are used.
Worked example
- Bore = 100 mm, Stroke = 100 mm, Cylinders = 1.
- Swept volume = (π ÷ 4) × 100² × 100 ÷ 1000.
- = 0.7854 × 10,000 × 100 ÷ 1000 = 785.398 cc.
- Displacement in litres = 785.398 ÷ 1000 = 0.7854 L.
Displacement = 785.40 cc (0.7854 L)
Common mistakes to avoid
- Entering bore and stroke in millimeters but expecting cubic-inch output -- the formula returns cc; divide by 16.387 to convert to cubic inches.
- Squaring the full bore diameter in the formula rather than realizing the (pi/4) x bore^2 form already handles a diameter input, not radius.
- Omitting one or more cylinders when comparing displacement to a manufacturer spec that uses all cylinders.
Key terms
- Bore
- The internal diameter of an engine cylinder, measured in millimeters.
- Stroke
- The distance the piston travels from top dead centre (TDC) to bottom dead centre (BDC), measured in millimeters.
- Displacement
- The total volume swept by all pistons during one complete stroke, expressed in cubic centimetres (cc) or litres.
- Swept volume
- The volume displaced by one piston over its full stroke — the same as displacement for a single-cylinder engine.
Frequently asked questions
- How is engine displacement calculated?
- Displacement (cc) = (π/4) × bore² × stroke × cylinders ÷ 1,000. This gives the swept volume of all pistons combined in cubic centimeters.
- What does engine displacement affect?
- Larger displacement generally means more potential power and torque, but also higher fuel consumption. Forced induction (turbo/supercharger) lets smaller engines produce more power.