Engine Displacement Calculator
Calculate engine displacement in cubic inches, liters, and cc from bore, stroke, and cylinders.
What it does
Engine displacement is the total volume swept by all pistons during one revolution. It is one of the basic size measures for a car, motorcycle, or small engine. Displacement influences airflow, torque, fuel use, and the class a vehicle competes in.
The calculation uses three measurements: bore, stroke, and cylinder count. Bore is the inside diameter of a cylinder. Stroke is the distance the piston travels from top to bottom. One cylinder sweeps a cylinder-shaped volume, and the engine repeats that volume for every cylinder.
The default example is a classic 350 cubic inch V8 with a 4.00 inch bore, 3.48 inch stroke, and 8 cylinders. It displaces 349.85 cubic inches, 5.73 liters, or 5,733 cubic centimeters. The metric defaults mirror the same engine at 101.6 mm bore and 88.392 mm stroke.
The formula assumes a circular cylinder with a flat top and bottom. It does not include the combustion chamber, head gasket, or any space above the piston at top dead center. Those volumes belong to the compression ratio calculation, not to displacement.
Use the tool to compare engines, check a rebuild, or convert a size from cubic inches to liters. For a precise build, measure the actual bore and stroke rather than relying on a nominal engine family name.
How to use
- Pick imperial or metric units.
- Enter the cylinder bore in inches or millimeters.
- Enter the piston stroke in the same unit system.
- Enter the number of cylinders.
- Press Calculate to update the result.
- Read the primary displacement, the other unit, and cubic centimeters.
Formula
- bore
- Cylinder diameter in inches or millimeters.
- stroke
- Piston travel in the same unit as the bore.
- cylinders
- Number of cylinders in the engine.
- Vd
- Total swept volume in cc, liters, or cubic inches.
Use the full bore, not the radius. The area of a circle is π/4 times the diameter squared. Multiply that area by stroke for one cylinder, then by the cylinder count. The engine converts inches to millimeters at 25.4, keeps volume in cc, divides by 1,000 for liters, and divides by 16.387064 for cubic inches. For 4.00 inches and 3.48 inches, bore is 101.6 mm and stroke is 88.392 mm, giving 349.85 cubic inches.
Worked example
Example: a 350 cubic inch V8
Defaults: imperial, 4.00 in bore, 3.48 in stroke, 8 cylinders.
- Convert bore: 4.00 x 25.4 = 101.6 mm.
- Convert stroke: 3.48 x 25.4 = 88.392 mm.
- Cylinder area: π/4 x 101.6² = 8,107.32 mm².
- One cylinder: 8,107.32 x 88.392 = 716,622.2 mm³, or 716.622 cc.
- All cylinders: 716.622 x 8 = 5,732.98 cc.
- Convert: 5,732.98 / 1,000 = 5.73 L; 5,732.98 / 16.387064 = 349.85 cu in.
- Tool shows 349.85 cu in, 5.73 L, and 5,733 cc.
Reference table
| Liters | Cubic inches | Cubic centimeters |
|---|---|---|
| 1.0 | 61.02 | 1,000 |
| 1.5 | 91.54 | 1,500 |
| 2.0 | 122.05 | 2,000 |
| 3.0 | 183.07 | 3,000 |
| 5.0 | 305.12 | 5,000 |
| 6.7 | 408.86 | 6,700 |
| 7.0 | 427.17 | 7,000 |
Limits
- The formula assumes a circular cylinder and a flat piston top.
- It does not include combustion chamber volume or head gasket volume.
- Rotary, oval, and heavily modified engines need a different geometry.
- Manufacturer displacement is often rounded, so the exact result may differ.
Common mistakes
- Using bore radius instead of bore diameter.
- Mixing inches and millimeters in the same calculation.
- Forgetting to multiply by the number of cylinders.
- Confusing engine displacement with compression ratio.
- Using a nominal engine size when the actual bore and stroke differ.
Try it yourself
Quick checks. Answers sit tucked under each question.
3.50 in bore, 3.00 in stroke, 6 cylinders?
173.18 cu in, 2.84 L, and 2,838 cc.
86 mm bore, 86 mm stroke, 4 cylinders?
2.00 L, 121.94 cu in, and 1,998 cc.
4.25 in bore, 4.00 in stroke, 8 cylinders?
453.96 cu in, 7.44 L, and 7,439 cc.
Questions
How do you calculate engine displacement?
Multiply π/4 by bore squared, then by stroke and cylinder count. Keep bore and stroke in the same units.
Why is a 350 cubic inch engine called a 5.7 L?
350 cubic inches is about 5,733 cc, which rounds to 5.7 liters. The tool shows 349.85 cu in and 5.73 L for the default dimensions.
Is bore radius or diameter?
Bore is the full diameter. If you only have the radius, use π x radius² x stroke x cylinders instead.
Does displacement include the combustion chamber?
No. Displacement is swept volume only. Chamber volume is used for compression ratio.
How many cc are in one cubic inch?
One cubic inch is 16.387064 cc. Divide cubic inches by 0.0610237441 to go the other way.
Does a larger displacement always mean more power?
No. Cylinder heads, cam timing, boost, fuel, and engine speed also shape power.
Sources
- Rose-Hulman Institute of Technology: ME410 engine geometry notes
- U.S. Nuclear Regulatory Commission: introduction to diesel engines