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Engine Displacement Calculator

Computes engine displacement from bore, stroke and cylinder count (V = π/4 × bore² × stroke × cylinders) in cc, litres and cubic inches, plus the per-cylinder volume and bore/stroke ratio.

When to use

You know an engine's bore and stroke and need its displacement, or want to check the effect of overboring or a stroker crank.

Do not use when: You need the compression ratio (use compression-ratio) or a rotary/Wankel engine (displacement is defined differently).

Formula

cylinder_volume_cc = π / 4 × (bore_mm / 10)² × (stroke_mm / 10); displacement_cc = cylinder_volume_cc × cylinders; displacement_l = displacement_cc / 1000; displacement_cubic_in = displacement_cc / 16.387064

Inputs

Parameter	Type	Unit	Required	Description
`bore_mm`	number	mm	yes	Cylinder bore diameter in millimetres (inches × 25.4). Range: > 0, ≤ 1000
`stroke_mm`	number	mm	yes	Piston stroke in millimetres (inches × 25.4). Range: > 0, ≤ 1000
`cylinders`	integer		default 4	Number of cylinders. Range: ≥ 1, ≤ 32

Outputs

Output	Type	Unit	Description
`cylinder_volume_cc`	number	cc	π/4 × bore² × stroke for one cylinder (swept volume).
`displacement_cc`	number	cc	Total swept volume in cubic centimetres.
`displacement_l`	number	L	Displacement in litres.
`displacement_cubic_in`	number	cu in	Displacement in cubic inches (1 cu in = 16.387064 cc).
`bore_stroke_ratio`	number		bore_mm / stroke_mm.
`engine_geometry`	string		Oversquare (bore > stroke), square, or undersquare (stroke > bore).

Example

86 mm × 86 mm, 4 cylinders: {"bore_mm":86,"stroke_mm":86,"cylinders":4} → {"cylinder_volume_cc":499.56,"displacement_cc":1998.2,"displacement_l":1.998,"displacement_cubic_in":121.94,"bore_stroke_ratio":1,"engine_geometry":"Square (bore = stroke)"}

Chevrolet 350: 4.00 in × 3.48 in, 8 cylinders: {"bore_mm":101.6,"stroke_mm":88.392,"cylinders":8} → {"displacement_cc":5733,"displacement_l":5.733,"displacement_cubic_in":349.85,"engine_geometry":"Oversquare (bore > stroke)"}

GET https://tttkmbb.com/api/v1/calculate/engine-displacement?bore_mm=86&stroke_mm=86&cylinders=4

Machine access

API: GET https://tttkmbb.com/api/v1/calculate/engine-displacement (query parameters) or POST with a JSON body {"inputs": {...}}
Schema: https://tttkmbb.com/api/v1/calculators/engine-displacement · Markdown: https://tttkmbb.com/engineering/engine-displacement.md · JSON definition: https://tttkmbb.com/engineering/engine-displacement.json
MCP: server https://tttkmbb.com/mcp, tool run_calculator with calculator_id="engine-displacement"
OpenAPI operationId: calculate_engine_displacement
Freshness: static. Authentication: none. Rate limit: fair use (see rate limits).

Sources

Wikipedia – Engine displacement (reference)
NIST Special Publication 811 – Guide for the Use of the SI, Appendix B (conversion factors) (standard)

FAQ

Why is a '2.0 L' engine not exactly 2000 cc?

Marketing names round the swept volume; the geometric displacement is often a few cc off (1,998 cc here) and tax classes use the exact figure.

Does displacement include the combustion chamber?

No. Displacement is the swept volume between top and bottom dead centre only; the chamber volume enters the compression ratio instead.

Related calculators

Compression Ratio Calculator — Static compression ratio from the same bore and stroke.
Cylinder Calculator — Volume of a cylinder in general.
Horsepower, Torque and RPM Calculator — Power and torque relation for the engine.