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Engine displacement calculator

Cubic inches, liters and cc from bore, stroke and cylinder count, with what common overbores do to it. Your numbers are saved to My Build so the carburetor and compression calculators can use them.

Enter your numbers
Engine

Displacement

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Total cc
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Per cylinder
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Bore / stroke ratio
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Rod / stroke ratio
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OverboreBoreCubic inchesLiters

Measure, don't assume

Machine shops often bore to fit specific pistons, so a "+.030" block can finish a little different. Use the finished bore from your machinist's sheet.

How displacement is calculated

Cubic inches = 0.7854 × bore² × stroke × cylinders
cc = cubic inches × 16.387

0.7854 is π ÷ 4, which turns the bore diameter into the area of the cylinder. Multiply by the stroke for one cylinder's swept volume, then by the number of cylinders.

Overbore

The overbore table assumes the block is bored to the listed oversize and the stroke stays the same. Overbores are listed in the usual machine-shop steps. Whether a block can take them depends on cylinder wall thickness, which only a sonic check can tell you.

Bore/stroke and rod ratio

Bore/stroke above 1 is "oversquare", which generally favors higher rpm. Rod ratio (rod length ÷ stroke) affects how quickly the piston moves near top dead center and how hard it pushes the rod against the cylinder wall. Most production V8s sit roughly between 1.5 and 1.9.

Frequently asked questions

Why does overboring change displacement so much for a small bore increase?

Displacement scales with the square of the bore diameter, so even a small increase in bore compounds across all cylinders — a common 0.030" overbore can add a meaningful handful of cubic inches on a V8, more than intuition alone might suggest.

Is cc or cubic inches the more useful number?

It depends on your audience — American builders and parts catalogs commonly reference cubic inches, while European specs and some import platforms use cc or liters, so this calculator gives you all three since which one is "standard" really depends on what you're working on.

What is "My Build" and why does it save my numbers?

It's a simple saved-profile feature — once you've entered your bore, stroke, and cylinder count here, the carburetor CFM and compression ratio calculators reuse those same saved numbers automatically, so you're not re-entering the same engine specs on every page.

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