Engine Displacement Calculator (cc, L, cu in)
How do you calculate engine displacement? Enter the bore, stroke and number of cylinders to get the swept volume of the whole engine in cubic centimetres, litres and cubic inches. The bore to stroke ratio tells you whether the engine is oversquare, square or undersquare. For the compression ratio of the same engine, use the compression ratio calculator.
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Formula
V = (pi / 4) x bore^2 x stroke x cylinders
bore to stroke ratio = bore / stroke
Volumes: 1 cc = 1 cm3 = 1000 mm3, 1 litre = 1000 cc, 1 cubic inch = 16.387064 cc (exact, from 1 in = 25.4 mm).
The ratio is labelled square when it rounds to 1.00, oversquare above 1 and undersquare below 1.
Worked example
A 4-cylinder engine with an 86 mm bore and 86 mm stroke:
- One cylinder: 0.7854 x 86 x 86 x 86 = 499,557 mm3 = 499.56 cc
- Four cylinders: 1998.2 cc, which is 1.998 L or 121.9 cubic inches
- Ratio: 86 / 86 = 1.00, a square engine
The classic 350 cubic inch V8 (4.00 in bore, 3.48 in stroke, 8 cylinders) gives 0.7854 x 16 x 3.48 x 8 = 349.8 cubic inches, which is 5733 cc, with a ratio of 1.15 (oversquare).
Use this when
You want to check a stated engine size, compare engines from different markets that quote cc, litres or cubic inches, or plan an overbore or a stroker kit. Typical road-car engines are roughly 1.0 to 3.0 L, and oversquare designs are common because they allow high revs.
Related calculators
The compression ratio calculator uses the same swept volume per cylinder but adds the combustion chamber. The power to weight ratio calculator compares output, not size: two engines of the same displacement can make very different power.
Common mistakes
- Using the piston diameter in cm and the stroke in mm without converting.
- Forgetting to multiply by the number of cylinders.
- Expecting the advertised size to match exactly. Manufacturers round to a convenient figure and bores carry tolerances.
- Confusing displacement with power; a bigger engine is not always stronger.
Frequently asked questions
How do you calculate engine displacement?
Multiply the area of one cylinder bore (pi/4 x bore squared) by the stroke and by the number of cylinders. For 86 mm x 86 mm and 4 cylinders that is 0.7854 x 86 x 86 x 86 x 4 = 1,998,229 mm3, or 1998 cc.
How do I convert cc to litres and cubic inches?
Divide cc by 1000 for litres, and divide cc by 16.387064 for cubic inches. 1998 cc is 1.998 L, sold as a 2.0 L engine, and 121.9 cubic inches.
What does oversquare mean?
An oversquare engine has a bore larger than its stroke (ratio above 1). It can rev higher for the same piston speed. A 4.00 in bore with a 3.48 in stroke has a ratio of 1.15. Undersquare engines have a longer stroke and usually favour low-rev torque.
Why does the advertised size differ from the calculated one?
Manufacturers round to a convenient figure, and measured bore and stroke carry small tolerances. A 349.8 cubic inch engine is sold as a 350, and 5733 cc is marketed as 5.7 L. Overbored engines grow slightly from stock.
How many litres is an engine with a 78 mm bore and 83.5 mm stroke?
A 4-cylinder with a 78 mm bore and 83.5 mm stroke displaces 1596 cc, which is 1.596 L (97.4 cubic inches) and is sold as a 1.6 L. Its ratio is 0.93, so it is undersquare.
How do I calculate a 350 cubic inch engine in cc and litres?
A 4.00 in bore, 3.48 in stroke and 8 cylinders gives 349.8 cubic inches, which is 5733 cc or 5.733 L. It is sold as a 350 or a 5.7 L, and its bore to stroke ratio is 1.15 (oversquare).
How many cc is a 3.0L six-cylinder engine per cylinder?
A 6-cylinder with an 89 mm bore and 80 mm stroke displaces 2986.1 cc, or 2.986 L. Divide by six to get about 497.7 cc per cylinder. The ratio is 1.11, so it is oversquare.