Quick answer
Displacement = π ÷ 4 × bore² × stroke × number of cylinders. An 86 mm bore, 86 mm stroke four-cylinder engine displaces 1,998.2 cc, which is 1.998 litres or 121.9 cubic inches.
Enter bore, stroke and the number of cylinders. The calculator returns total displacement in cc, litres and cubic inches.
Related tools: Compression Ratio Calculator: Static compression ratio from bore, stroke and clearance volume. Horsepower Calculator: Power from torque and engine speed. Carburetor Size Calculator: Carburetor airflow needed from displacement, peak rpm and volumetric efficiency.
How to use the Engine Displacement Calculator
- Enter bore (mm) (above 0).
- Enter stroke (mm) (above 0).
- Enter cylinders (a whole number, between 1 and 24).
- Press Calculate to see the result, and use Reset to start again.
| Input | What to enter | Allowed values |
|---|---|---|
| Bore | A number, in mm | > 0 |
| Stroke | A number, in mm | > 0 |
| Cylinders | A whole number | ≥ 1, ≤ 24 |
Formula and method
Formula
displacement = π/4 × bore² × stroke × cylinders
IEEE-754 double precision; shown to the decimals indicated.
1 cubic inch = 16.387064 cm³ exactly.
Worked examples
These examples are verified: each one is an automated test case that the live calculator must reproduce exactly.
Example 1
Inputs: Bore = 86; Stroke = 86; Cylinders = 4.
| Result | Value |
|---|---|
| Displacement | 1,998.2 cc |
| In liters | 1.998 L |
| In cubic inches | 121.9 ci |
Example 2
Inputs: Bore = 99; Stroke = 92; Cylinders = 6.
| Result | Value |
|---|---|
| Displacement | 4,249.1 cc |
| In liters | 4.249 L |
| In cubic inches | 259.3 ci |
Example 3
Inputs: Bore = 101.6; Stroke = 88.9; Cylinders = 8.
| Result | Value |
|---|---|
| Displacement | 5,765.9 cc |
| In liters | 5.766 L |
| In cubic inches | 351.9 ci |
The first line is the headline result (displacement). Below it the engine Displacement Calculator lists in liters and in cubic inches, which describe the same case from other angles. IEEE-754 double precision; shown to the decimals indicated.
Reading the result
Each cylinder sweeps 0.7854 × 8.6² × 8.6 = 499.6 cc; four of them give 1,998.2 cc, sold as a '2.0 litre' engine. Displacement is the volume the pistons sweep in one stroke, not the engine's power.
Square, over-square and under-square
When bore equals stroke the engine is called square, as here. A larger bore than stroke (over-square) favours high revs; a longer stroke favours low-speed torque. Use the same unit for bore and stroke.
How the result changes with bore
Holding every other input at the first worked example, this table changes only bore. It shows how sensitive the answer is to that one value; each row was produced by running this calculator.
| Bore | Displacement | In liters | In cubic inches |
|---|---|---|---|
| 43 | 499.6 cc | 0.5 L | 30.5 ci |
| 86 | 1,998.2 cc | 1.998 L | 121.9 ci |
| 172 | 7,992.9 cc | 7.993 L | 487.8 ci |
| 344 | 31,971.7 cc | 31.972 L | 1,951 ci |
What happens with invalid input
These messages are produced by the calculator itself, so you know what to fix.
- Bore: entering "0" shows "Bore must be greater than 0." beside that field and no result.
- Cylinders: entering "0" shows "Cylinders must be at least 1." beside that field and no result.
Choosing between the Engine Displacement Calculator and similar calculators
Each row shows what a related calculator on this site asks for and what it returns, so you can pick the one that matches your question.
| Calculator | You enter | It returns |
|---|---|---|
| [Compression Ratio Calculator](/automotive/compression-ratio-calculator/) | bore, stroke and clearance volume per cylinder | Compression ratio |
| [Horsepower Calculator](/automotive/horsepower-calculator/) | torque, torque unit and engine speed | Power |
| [Carburetor Size Calculator](/automotive/carburetor-size-calculator/) | displacement, peak engine speed and volumetric efficiency | Required airflow |
| [Engine Torque Calculator](/engineering/engine-torque-calculator/) | calculate and engine speed | Torque |
| [Fuel Savings Calculator](/automotive/fuel-savings-calculator/) | miles driven per year, current fuel economy and new fuel economy | Annual savings |
Background: vehicle sizing and speed
A taller tyre travels farther per revolution, so the speedometer reads low and the effective gear ratio becomes numerically lower; a shorter tyre does the opposite. True speed is roughly the speedometer reading times the new tyre diameter divided by the old one. Verify with GPS over a known distance before changing parts.
Assumptions and limitations
- Use consistent units
If a required value is empty, not a number, or outside its allowed range, the form marks that field with a message and shows no result instead of a misleading number. The automated checks deliberately try invalid entries for bore and cylinders to confirm this.
Frequently asked questions
How do I convert cc to litres?
Divide by 1,000: 1,998 cc is about 2.0 L.
How many cubic inches in a litre?
One litre is about 61.02 cubic inches.
Does displacement set horsepower?
No, but larger engines usually have more potential torque.
What does the Engine Displacement Calculator calculate?
Displacement from bore, stroke and number of cylinders. It returns Displacement, In liters and In cubic inches.
What formula does the Engine Displacement Calculator use?
displacement = π/4 × bore² × stroke × cylinders. 1 cubic inch = 16.387064 cm³ exactly.
What do I need to enter in the engine Displacement Calculator?
You enter Bore (mm), Stroke (mm) and Cylinders.
How is the result rounded or limited?
IEEE-754 double precision; shown to the decimals indicated. Use consistent units.
What is an example of a engine Displacement result?
With bore 86, stroke 86 and cylinders 4, the displacement is 1,998.2 cc.
Related calculators
- Compression Ratio Calculator — Static compression ratio from bore, stroke and clearance volume.
- Horsepower Calculator — Power from torque and engine speed.
- Carburetor Size Calculator — Carburetor airflow needed from displacement, peak rpm and volumetric efficiency.
- Fuel Savings Calculator — Yearly fuel savings from a more efficient vehicle.
- Distance per Tank Calculator — Range on a full tank from tank size and fuel economy.
Sources
- OpenStax, Prealgebra 2e (Rice University): fractions, decimals, percents, ratios and rounding
- NIST Special Publication 811, Guide for the Use of the International System of Units (SI), Appendix B conversion factors (international inch 25.4 mm, avoirdupois pound 0.45359237 kg)
Content last reviewed 2026-11-04. Formulas and worked examples are checked by automated tests against independently computed values.