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Walk-through

How to Use This Calculator

3 steps

1

Enter bore, stroke, and cylinder count

Type in the cylinder bore (the cylinder's inside diameter) and stroke (the distance the piston travels), both in millimeters, plus the number of cylinders. The calculator defaults to 86mm bore, 86mm stroke, and 4 cylinders — a common midsize four-cylinder layout — so you always see a live example.

2

Read the total displacement

The result card shows total displacement in liters, cubic centimeters (cc), and cubic inches (ci) — the three units engines are most commonly advertised in. The Units tab lists the same figure in every unit side by side, plus the swept volume of a single cylinder.

3

Check the bore/stroke ratio

Switch to the Bore/Stroke tab to see whether the engine is oversquare (bore larger than stroke), undersquare (stroke longer than bore), or square (roughly equal). This ratio is a quick signal for whether an engine is tuned for high-RPM power or low-RPM torque.

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Reference

Formula & Methodology

1 formula

Displacement formula

displacement = (π / 4) × bore² × stroke × cylinders

Each cylinder is modeled as a circular cylinder of swept volume: cross-sectional area (π/4 × bore²) times stroke length. Multiplying by the number of cylinders gives total engine displacement. Bore and stroke are in millimeters, so the raw result is in cubic millimeters; dividing by 1,000 converts to cubic centimeters (cc), and dividing cc by 1,000 again gives liters. Cubic inches = cc ÷ 16.387064, the exact number of cubic centimeters in one cubic inch.

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Glossary

Key Terms Explained

6 terms

Displacement The total swept volume of all cylinders in an engine — the amount of air/fuel mixture the engine can draw in during one full cycle. Usually quoted in liters (e.g. "2.0L") or cubic centimeters (e.g. "1998cc").

Bore The inside diameter of a cylinder, measured in millimeters or inches. A larger bore increases the cylinder's cross-sectional area and, all else equal, its displacement.

Stroke The distance the piston travels from top dead center to bottom dead center inside the cylinder, set by the crankshaft's throw. A longer stroke increases swept volume but also increases piston speed at a given RPM.

Cylinder One combustion chamber of the engine. Total displacement is the swept volume of a single cylinder multiplied by the number of cylinders — four, six, and eight are the most common counts in passenger vehicles.

cc (cubic centimeter) A metric volume unit equal to one milliliter. Engine displacement in cc divided by 1,000 gives liters; multiplying liters by 1,000 gives cc back.

Cubic inch An imperial volume unit historically used to describe American engine sizes (e.g. a "350" small-block is 350 cubic inches, about 5.7L). One cubic inch equals 16.387064 cc.

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Scenarios

Real-World Examples

3 worked examples

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Midsize four-cylinder

86mm bore, 86mm stroke, 4 cylinders

Bore 86 mm Stroke 86 mm Cylinders 4

This is a square engine (bore equals stroke), a very common layout for modern four-cylinder engines. Total displacement works out to about 2.0 liters — 1,998 cc, or roughly 122 cubic inches — the exact spec of many popular 2.0L turbocharged four-cylinder engines.

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Converting between units

A 5.7-liter V8 in cubic inches

Displacement 5,700 cc Conversion cc ÷ 16.387064

5,700 cc ÷ 16.387064 ≈ 347.8 cubic inches, close to the classic American "350" small-block naming convention (which is nominally 5.7L / 350 ci, with the exact figure rounded for marketing). Cubic inches and liters describe the same physical volume — only the unit differs.

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Oversquare vs. undersquare

Same displacement, different bore/stroke split

Engine A 100mm bore / 80mm stroke (oversquare) Engine B 80mm bore / 100mm stroke (undersquare)

Both engines can produce a similar total displacement, but Engine A's larger bore and shorter stroke let it rev higher with lower piston speed — favoring high-RPM power, common in sports and racing engines. Engine B's longer stroke increases torque at low RPM and is typical of diesel and economy-focused engines.

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Deep Dive

Understanding Engine Displacement

3 chapters · 3 min read

Engine displacement is the single number that most concisely describes how much air and fuel an engine can process per cycle, and it's the starting point for comparing engines across brands, eras, and unit systems. This calculator turns the three physical dimensions — bore, stroke, and cylinder count — into the liter, cc, and cubic-inch figures engines are actually marketed in.

How the Engine Displacement Calculator works

Each cylinder is treated as a right circular cylinder: its cross-sectional area is π/4 × bore², and multiplying that area by the stroke length gives the swept volume of one cylinder. Multiplying by the number of cylinders gives the engine's total displacement. The math is exact geometry — it assumes a perfectly cylindrical bore and a piston that travels the full stroke distance, which is how displacement is officially specified by every manufacturer.

Inputs and what they mean

Bore and stroke are both entered in millimeters, the unit used on virtually every modern engine spec sheet (older American engines are sometimes quoted in inches — multiply by 25.4 to convert to millimeters first). Cylinder count should be a whole number matching the engine's layout (e.g. 4, 6, 8). Because displacement scales with the square of the bore but only linearly with stroke and cylinder count, a small increase in bore has an outsized effect on the result — a common reason engine builders "bore out" a block to add displacement.

Limits and edge cases

This calculator computes theoretical geometric displacement only. It does not account for deck clearance, dished or domed pistons, or valve reliefs, all of which slightly change the actual combustion chamber volume used for compression ratio calculations (a separate figure). It also assumes every cylinder is identical, which holds for virtually all production engines but not for some exotic or asymmetric designs. For compression ratio, combustion chamber volume, and head gasket thickness also matter — those require a dedicated compression ratio calculation, not just bore and stroke.

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Questions

Frequently Asked Questions

6 questions

What is the engine displacement formula?+

Displacement = (π/4) × bore² × stroke × cylinders, where bore and stroke are in millimeters. This gives the result in cubic millimeters; dividing by 1,000 converts to cubic centimeters (cc).

How do I convert cc to liters?+

Divide cubic centimeters by 1,000. For example, 1,998 cc ÷ 1,000 = 1.998 liters, commonly rounded and marketed as a "2.0L" engine.

How do I convert cc to cubic inches?+

Divide cubic centimeters by 16.387064 (the exact number of cc in one cubic inch). For example, 1,998 cc ÷ 16.387064 ≈ 121.9 cubic inches.

What does oversquare mean?+

Oversquare means the cylinder bore is larger than the piston stroke (bore/stroke ratio greater than 1.00). Oversquare engines have lower piston speed at a given RPM, which typically lets them rev higher — a common trait of performance and racing engines.

Why does bore/stroke ratio matter?+

It's a quick signal of an engine's character: oversquare engines (bore > stroke) tend to favor high-RPM power and quicker throttle response, while undersquare engines (stroke > bore) tend to favor low-RPM torque and efficiency. Square engines (bore ≈ stroke) split the difference.

What units does this calculator use?+

Bore and stroke are entered in millimeters, and cylinder count as a whole number. Results are shown in liters (L), cubic centimeters (cc), and cubic inches (ci) — the three units engine displacement is conventionally advertised in.

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Unit	Value
Liters (L)	—
Cubic centimeters (cc)	—
Cubic inches (ci / cu in)	—
Cubic centimeters per cylinder	—

Engine Displacement Calculator

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