Engine Displacement Calculator

Quick Answer

Last updated: 3 November 2026 ·How we calculate this: the swept-volume formula

How This Engine Displacement Calculator Works

Enter the bore, which is the width of each cylinder, and the stroke, which is how far each piston travels from top to bottom. Choose millimeters or inches, then enter the number of cylinders. The calculator finds the volume each piston sweeps, multiplies it by the number of cylinders, and shows the total in cc, liters and cubic inches.

It also shows the stroke to bore ratio, which tells you whether the engine is built for high revs or for low-down pulling power, and the rounded size that makers usually put on the badge.

How to Use the Engine Displacement Calculator

1. Enter the bore, the width of each cylinder.
2. Enter the stroke, how far each piston travels.
3. Choose millimeters or inches.
4. Enter the number of cylinders.
5. Press Calculate and read the displacement in cc, liters and cubic inches.

Core Formulas

• One cylinder: V = π ÷ 4 × bore² × stroke
• Engine: displacement = V × number of cylinders
• Liters: cc ÷ 1,000
• Cubic inches: cc ÷ 16.387064
• From inches: cu in = 0.7854 × bore² × stroke × cylinders

The cubic-inch factor is exact because one inch is defined as exactly 2.54 cm, so one cubic inch is 2.54³ = 16.387064 cc.

Key Terms

• Bore: the diameter of a cylinder.
• Stroke: the distance a piston travels between its highest and lowest points.
• Displacement: the total volume swept by all pistons in one full turn of the stroke.
• cc: cubic centimeters, where 1,000 cc equals 1 liter.
• Oversquare: an engine whose bore is larger than its stroke.

Worked Example

A V8 has a 4.00 in bore and a 3.48 in stroke.

• One cylinder = 0.7854 × 4.00² × 3.48 = 43.73 cu in
• Engine = 43.73 × 8 = 349.85 cu in
• In cc: 349.85 × 16.387064 = 5733 cc, about 5.7 liters

That is why an engine like this is often called a "350" in the US and a 5.7-liter elsewhere.

Real-Life Examples

• Checking a spec sheet: 86 mm × 86 mm × 4 cylinders is 1998.23 cc, a 2.0-liter engine.
• Motorcycles: a 67 mm bore and 42.5 mm stroke with 4 cylinders is 599.36 cc, a 600 cc class bike.
• Classic V8s: 4.00 in × 3.48 in × 8 is 349.85 cubic inches.
• Engine builds: see how much a 1 mm overbore adds before machining.

Displacement vs Compression Ratio

• Displacement: the volume the pistons sweep, which sets engine size.
• Compression ratio: total cylinder volume at the bottom ÷ volume at the top, which affects efficiency and fuel needs.
• Link: compression ratio = (swept volume + chamber volume) ÷ chamber volume.

Displacement per Cylinder by Bore and Stroke

Bore, Stroke and Engine Character

• Oversquare (bore bigger than stroke): short piston travel lets the engine rev higher. Common in sports bikes and race engines.
• Undersquare (stroke bigger than bore): long piston travel gives strong pulling at low revs. Common in diesels and economy engines.
• Square: bore and stroke about equal, a balance between the two.
• Displacement is not power: turbochargers, valve timing and revs matter as much as size.

Boring Out and Stroker Kits

Engine builders raise displacement by boring the cylinders wider or by fitting a crankshaft with a longer stroke. Because bore is squared in the formula, a small overbore makes a noticeable difference. Boring the 86 mm four-cylinder above by 1 mm, to 87 mm, takes it from 1998.23 cc to 2044.97 cc, an increase of 46.74 cc.

Use the calculator to test changes before you buy parts. Enter the new bore or stroke and compare the totals. Always check that the block has enough wall thickness and that your racing class or local rules allow the change.

Common Mistakes to Avoid

• Using the radius instead of the diameter. Bore is the full width of the cylinder.
• Mixing units. Bore in mm and stroke in inches gives nonsense. Use one unit for both.
• Forgetting to multiply by cylinders. One cylinder's volume is not the engine size.
• Including the combustion chamber. Displacement is swept volume only.
• Expecting the badge number exactly. Makers round, so 1,998 cc is sold as 2.0 L.

Frequently Asked Questions

References & Sources