Engine Math
Engine Displacement Calculator
Calculate engine displacement in cc, liters, and cubic inches from bore, stroke, and cylinder count — and compare stock vs. overbore or stroker builds side by side.
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How to Use This Tool
- Choose millimeters or inches to match your spec sheet or machine-shop ticket.
- Enter the stock bore, stroke, and number of cylinders.
- Enter the build bore and stroke — for example a +0.5 mm overbore or a stroker crank.
- Compare cc, liters, and cubic inches plus the change, then carry the same bore and stroke into the compression ratio calculator.
The Formula & Physics Behind the Math
Each cylinder sweeps a cylinder-shaped volume: swept volume = π ÷ 4 × bore² × stroke. Total displacement = swept volume × number of cylinders. With bore and stroke in centimeters the result is in cubic centimeters (cc); divide by 1,000 for liters and by 16.387 for cubic inches. Because bore is squared, a small overbore adds less than you might expect, while a longer stroke adds displacement in direct proportion — an 86 × 86 mm four-cylinder is 1,998 cc, and stroking it to 94 mm makes 2,184 cc.
Frequently Asked Questions
How do I calculate engine displacement?
Multiply π ÷ 4 by the bore squared, then by the stroke, then by the number of cylinders. With measurements in centimeters you get cubic centimeters. A Chevy 350 with a 4.000 in bore and 3.480 in stroke across eight cylinders works out to about 349.9 cubic inches (5.7 L).
Does overboring or a stroker crank add more displacement?
Stroke adds displacement linearly, so a 10% longer stroke adds 10%. Bore adds with the square of the diameter, so a typical 0.5 mm or 0.020 in overbore adds only around 1%. Stroker kits are how builders make big displacement gains; overbores mostly clean up worn cylinders.
Why does my engine's advertised size differ slightly from the result?
Manufacturers round marketing figures — a 1,998 cc engine is sold as a 2.0 L. Published bore and stroke are also rounded to a tenth of a millimeter, so small differences are normal.
Does displacement change the compression ratio?
Yes. Larger swept volume with the same chamber, gasket, and piston volume raises static compression. After an overbore or stroker, recalculate with the Static Compression Ratio calculator before choosing pistons or a head gasket.