Engine Displacement Calculator (Bore and Stroke)
Engine displacement is the total swept volume of all the cylinders as the pistons move from top dead centre to bottom dead centre. Enter bore, stroke and the number of cylinders to see it in cc, cubic inches and liters.
Engine displacement
Enter bore, stroke and cylinder count. Results update as you type.
Cylinder diameter, as cast or after any overbore.
Distance the piston travels from top to bottom.
Whole number from 1 to 16.
Added to the bore. Leave 0 for none.
- Total (cubic inches)
- 349.85
- Total (liters)
- 5.733
- Per cylinder (cc)
- 716.6
- Per cylinder (cu in)
- 43.73
- Effective bore
- 4.000 in
- Bore / stroke ratio
- 1.149 - oversquare (short stroke)
How displacement is calculated
Each cylinder sweeps a volume shaped like a tall disc. The area of that disc is pi divided by 4, multiplied by the bore squared. Multiply that area by the stroke and you have the swept volume of a single cylinder.
In words: swept volume per cylinder = (pi / 4) x bore x bore x stroke. Total displacement = swept volume per cylinder x number of cylinders.
An overbore makes the bore larger, so it increases displacement. Enter the overbore amount and the calculator adds it to the bore before doing any of the maths, so the result reflects the finished size.
The bore to stroke ratio describes the shape of the engine. Oversquare means the bore is larger than the stroke (a short stroke engine). Undersquare means the stroke is longer than the bore (a long stroke engine). Square means the two are effectively equal.
Worked example
Work through the same numbers used in the automated tests: a bore of 4.000 in, a stroke of 3.480 in and 8 cylinders.
- Bore
- 4.000 in
- Stroke
- 3.480 in
- Cylinders
- 8
- Swept volume per cylinder
- 43.73 cu in
- Swept volume per cylinder
- 716.6 cc
- Total displacement
- 349.85 cu in
- Total displacement
- 5,733.0 cc
- Total displacement
- 5.733 L
- Bore / stroke ratio
- 1.149 (oversquare)
Frequently asked questions
What is engine displacement?
It is the combined swept volume of every cylinder, measured as the pistons travel from top to bottom. It is usually quoted in cubic inches, cc or liters, and it is where rounded engine names such as 350 or 2.0 litre come from.
What does oversquare mean?
Oversquare means the bore is bigger than the stroke. These engines can rev more freely because the piston speed is lower for a given rpm. Undersquare engines have a longer stroke than bore and tend to make their power lower in the rev range.
How do I measure bore and stroke?
Bore is the cylinder diameter, best measured with a bore gauge at several heights. Stroke is the distance the piston travels, which equals the crankshaft throw multiplied by two. When in doubt, use the figures published for your exact engine and note any overbore.
Why is a 350 engine not exactly 350 cubic inches?
Engine names are rounded. A 4.000 in bore with a 3.480 in stroke in a V8 works out to 349.85 cubic inches, which is rounded to 350. Wear, a fresh overbore or a different crankshaft can all move the true figure slightly.
How does an overbore change displacement?
Displacement grows with the square of the bore, so a small overbore has a slightly larger effect than a beginner might expect. A 0.030 in overbore on a 4.000 in cylinder increases the total displacement by roughly one percent.
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Last updated: October 11, 2026