Engine Displacement
Engine displacement from bore, stroke and cylinders in cc, litres and cubic inches — or the bore or stroke that gives a target capacity; bore/stroke ratio.
Per-cylinder and total displacement in cc, L and in³ with exact conversion, the bore-to-stroke ratio, and the dimension needed to reach a target displacement.
Example: 86 × 86 mm × 4 = 1,998 cc (2.0 L, 121.9 in³); a 4.030 × 3.750 in V8 is 382.7 in³ = 6,271 cc.
Bore squared,
times the stroke.
The cylinder-volume formula, the exact conversions between cc, litres and cubic inches, the reverse question, and why catalogue capacities are rounded.
The formula
One cylinder displaces π/4 × bore² × stroke; the engine displaces that times the cylinder count. With bore and stroke in millimetres the result is in cubic millimetres — divide by 1,000 for cc. A litre is 1,000 cc, and a cubic inch is exactly 16.387064 cc because an inch is exactly 25.4 mm.
Bore or stroke for a target
Solving the same equation the other way: for a wanted displacement and a known stroke, bore = √(4 V ÷ (π × stroke × n)); for a known bore, stroke = 4 V ÷ (π × bore² × n). These give the geometric figure for an overbore or a stroker; whether the block and crank allow it is not this page’s question.
Nominal figures
Marketed capacities are rounded: a “2.0 L” engine may be 1,998 cc and a “5.7 L” 5,733 cc. Tax classes and racing formulas use the calculated figure from the actual bore and stroke, so an overbore can cross a threshold. The bore-to-stroke ratio (over 1 = oversquare) is shown for reference.
What the number does not settle
Power, torque and efficiency depend on far more than displacement; see Horsepower & Torque for the relation between them at a given rpm and Compression Ratio for the clearance volumes. Inputs stay in your browser; the same four anonymous usage counts as the rest of the site apply.