Engine Displacement Calculator (Bore × Stroke)
Bore, stroke and cylinder count → cc, litres and cubic inches — plus bore/stroke ratio and what over-boring or stroking actually buys.
Bore/stroke ratio is the engine's personality: over-square (>1, big bore) breathes and revs — sport bikes run 1.3+; under-square (<1, long stroke) torques and economizes — modern eco fours and diesels live there. Exactly 1.0 is 'square' (the classic 86×86).
Formula
⚠️ Estimates for planning and education — verify against manufacturer data and measured results. Performance figures are not a substitute for safe, legal driving.
Bore, stroke and cylinder count → cc, litres and cubic inches — plus bore/stroke ratio and what over-boring or stroking actually buys.
About Engine Displacement Calculator (Bore × Stroke)
Every engine's headline number is just cylinder geometry: π/4 times bore squared, times stroke, times the cylinder count. This calculator turns bore and stroke (mm or inches) into cc, litres and cubic inches, computes the bore/stroke ratio that defines an engine's character, and handles the conversions between the metric world's 1998 cc and the muscle-car world's 350 ci without rounding lies.
How to use Engine Displacement Calculator (Bore × Stroke)
- 1Enter — sensible defaults are pre-filled so you see a worked result immediately.
- 2Read the live results: .
- 3Check the "With your numbers" line to see the formula displacement = π/4 × bore² × stroke × cylinders; 1 L = 61.024 ci, 1 ci = 16.387 cc substituted step by step.
- 4Adjust inputs (or flip the unit toggle) until the scenario matches yours, then copy or share the result.
Why use Engine Displacement Calculator (Bore × Stroke)?
- ✓Instant, free and private — every calculation runs in your browser, nothing is uploaded
- ✓Built on the published formula displacement = π/4 × bore² × stroke × cylinders; 1 L = 61.024 ci, 1 ci = 16.387 cc with sources cited on the page
- ✓Bore/stroke ratio is the engine's personality: over-square (>1, big bore) breathes and revs — sport bikes run 1.3+; under-square (<1, long stroke) torques and economizes — modern eco fours and diesels live there. Exactly 1.0 is 'square' (the classic 86×86).
- ✓Switch units, tweak any input and watch every result update live
Frequently asked questions
Why is a '2.0L' engine actually 1998 cc?+
Marketing rounds, geometry doesn't: an 86×86 mm four computes to 1998.2 cc, sold as 2.0L. Tax classes drive the precision in much of the world — many countries band engine tax at 1000/1500/2000 cc, so manufacturers design to land just under: 1498, 1998, 2998 cc engines are deliberate legal engineering. Japan's kei cars (660 cc cap) and India's sub-4m tax rules (1200 petrol/1500 diesel) created entire engine families pinned at the limit.
What does over-boring an engine do to displacement?+
Displacement grows with bore SQUARED, so small overbores pay quadratically: a 0.030″ overbore on a Chevy 350 (4.00→4.03″ bore) adds about 5 ci. But the real gains of a rebuild come from stroker cranks — stroke enters linearly yet can change far more: the classic 350→383 'stroker' pairs a 0.030 overbore with a 3.48→3.75″ crank. Bore is limited by cylinder-wall thickness; stroke by rod clearance and piston speed.
Why do high-revving engines choose big bore over long stroke?+
Mean piston speed = 2 × stroke × RPM caps the stroke: at the ~25 m/s durability ceiling, a 96-mm-stroke engine maxes near 7800 RPM while a 48-mm stroke allows 15,600. Big bores also fit bigger valves for breathing at those speeds. The price: a wide, shallow combustion chamber with longer flame travel — worse efficiency and emissions — which is exactly why economy-minded engines went long-stroke while sport bikes and F1 went extreme over-square.
How do cc and cubic inches translate for classic engines?+
Divide cc by 16.387: the legendary pairs are 5733 cc = 350 ci, 6997 = 427, 7456 = 455; going the other way, Europe's 1998 cc is 121.9 ci. Mind that classic 'advertised' displacements rounded freely (Pontiac's 455 computes to 456.6) and modern marketing keeps the tradition — Dodge's '392' HEMI is 6.4L = 390.6 ci. The geometry on this page is the arbiter; the badge is poetry.
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