Engine Displacement Calculator

Convert bore and stroke measurements to cubic inches (CID), cubic centimeters (cc), and liters. Includes an overbore simulator for machine shop work.

Engine Block Specifications
Cylinder Bore Diameter
Piston Stroke Length
Number of Cylinders
Swept Volume Output
Enter bore and stroke above to calculate displacement.
Overbore / Boring Over Simulator

Select a standard machine shop overbore increment to see the new displacement and net gain.

Select an overbore above after entering bore and stroke values.
Key Terms Explained
Engine Displacement
The total swept volume of all pistons in all cylinders, from BDC to TDC. Expressed in cubic inches (CID), cubic centimeters (cc), or liters (L).
Cylinder Bore
The diameter of the cylinder hole bored into the engine block. A larger bore means a wider piston and more swept area per stroke.
Piston Stroke
The distance the piston travels from its lowest point (BDC) to its highest point (TDC). A longer stroke increases displacement and typically adds low-end torque.
Cubic Inch (CID)
Cubic Inch Displacement. The traditional American unit for engine size. One CID equals exactly 16.387 cubic centimeters.
Cubic Centimeter (cc)
The metric unit of engine volume. 1000 cc equals 1 liter. Commonly used for motorcycle and small-displacement engines.
Top Dead Center (TDC)
The highest position of the piston inside the cylinder. At TDC, the piston has completed its compression or exhaust stroke.
Bottom Dead Center (BDC)
The lowest position of the piston in the cylinder. Maximum cylinder volume occurs at BDC, at the start of the compression stroke.
Overboring
Machining the cylinder walls to a larger diameter to remove wear, restore roundness, or increase displacement. Requires matched oversized pistons.

The Complete Guide to Engine Displacement Math

Whether you are rebuilding a classic V8, spec'ing a new crate motor, or just trying to understand what that liter number on the badge actually means, this guide walks through every aspect of engine displacement calculation from the ground up.

How to Use This Calculator

Enter your bore diameter and stroke length in the left panel. Each measurement has its own unit toggle, so you can mix inches and millimeters if your spec sheet uses both. Select the number of cylinders using the quick grid or enter a custom count. Every field recalculates in real time without a submit button. The right panel immediately displays displacement in cubic inches, cubic centimeters, and liters. Use the Overbore Simulator at the bottom to model machine shop work before you commit to a cut.

The Displacement Formula in Detail

The swept volume of a single cylinder is the volume of a cylinder (a geometric shape): Pi multiplied by the radius of the bore squared, then multiplied by the stroke length. Total engine displacement multiplies that by the number of cylinders.

Single Cylinder Volume = Pi x (Bore / 2)^2 x Stroke
Total Displacement (CID) = Single Cylinder Volume x Number of Cylinders
Cubic Centimeters (cc) = CID x 16.387064
Liters (L) = cc / 1000

Example: A classic Chevy 350 Small Block has a 4.000 inch bore and a 3.480 inch stroke with 8 cylinders. Plug in the numbers: Pi x (2.000)^2 x 3.480 x 8 = 3.14159 x 4.000 x 3.480 x 8 = 350.45 CID, which converts to 5,741.6 cc, or 5.742 liters. The rounded marketing figure is 5.7L.

Why Bore Has a Bigger Impact Than Stroke

Because bore appears as a squared term in the formula, even small increases to bore diameter have a compounding effect on displacement. Increasing bore by 0.030 inches raises the swept area by a factor of the new radius squared vs. the old radius squared, multiplied across every cylinder. A longer stroke linearly scales displacement, but a wider bore scales it geometrically. This is why performance builders often prioritize bore over stroke when looking for displacement gains within a fixed block architecture.

Understanding the Overbore Simulator

When an engine accumulates miles, the cylinder walls develop microscopic wear and lose their perfect circular shape (called "out of round"). A machine shop bores the cylinders to a larger, perfectly round diameter, removing between 0.010 and 0.060 inches of material depending on the wear and the desired outcome. The standard increments (0.020, 0.030, 0.040, 0.060) correspond to available oversized piston sets from major manufacturers. This simulator adds the overbore amount to your current bore, recalculates total displacement, and shows the net gain in CID and cc so you can plan your rebuild before the engine is on the machine.

Converting Between CID, CC, and Liters

The conversion factor between cubic inches and cubic centimeters is exactly 16.387064. This comes from the fact that one inch equals exactly 25.4 millimeters, and one cubic inch is therefore 25.4^3 = 16,387.064 cubic millimeters, or 16.387064 cubic centimeters. Liters are simply centiliters divided by 1000. These relationships are exact by definition under the international measurement conventions adopted in 1959, so the conversions in this calculator carry full mathematical precision limited only by floating point arithmetic.

Frequently Asked Questions

What is engine displacement and how does it affect horsepower? ▼
Engine displacement is the total swept volume of all pistons inside the cylinders, measured from Bottom Dead Center (BDC) to Top Dead Center (TDC). A larger displacement means more air and fuel can enter the cylinders per cycle, which generally produces more torque and horsepower. However, displacement alone does not determine output. Compression ratio, valve timing, fuel delivery, forced induction, and engine tuning all interact with displacement to set the final power figure. A well-tuned 350 CID engine can easily outperform a neglected 454.
Why do we measure some engines in Liters and others in Cubic Inches? ▼
The difference is regional convention and era. American muscle cars and hot rods historically used cubic inches because the United States used the imperial measurement system. European and Japanese automakers adopted the metric system, so their displacement is expressed in cubic centimeters (cc) or liters (L). Today, liters have become the dominant global standard for marketing engine size, but the cubic inch remains deeply embedded in American motorsport and the performance aftermarket. One cubic inch equals 16.387 cubic centimeters.
How does boring out a cylinder change the engine's displacement? ▼
Boring a cylinder removes a small amount of metal from the cylinder wall to enlarge the bore diameter. Because displacement is calculated using the bore radius squared (Pi times radius squared times stroke), even a small increase in bore has a compounding effect on volume. A common overbore of 0.030 inches on a V8 engine can add 5 to 8 cubic inches of total displacement depending on the original bore size and stroke. Machine shops offer standard overbore increments of 0.020, 0.030, 0.040, and 0.060 inches, each requiring matching oversized pistons.
What is the mathematical formula for calculating cubic inches? ▼
The formula is: Displacement = Pi x (Bore / 2) squared x Stroke x Number of Cylinders. Bore and Stroke must both be in inches for the result to be in cubic inches. For example, a 4.000 inch bore, 3.480 inch stroke, 8-cylinder engine: Pi x (2.000)^2 x 3.480 x 8 = 3.14159 x 4.000 x 3.480 x 8 = 350.45 cubic inches. To convert to cubic centimeters, multiply CID by 16.387. To get liters, divide cc by 1000.
Is a 350 cubic inch engine exactly 5.7 Liters? ▼
Not exactly, but very close. A true 350 CID engine displaces 350 x 16.387 = 5,735.45 cc, which rounds to 5.7 liters. The Chevrolet Small Block 350 V8 is the most famous example, and GM marketed it as the 5.7L in later fuel-injected variants. The rounding is standard industry practice: manufacturers round displacement to one decimal place in liters for marketing. This tool displays the exact liter value to three decimal places so you can see the true conversion, not the rounded label.