Engine Displacement Calculator
Convert bore, stroke and cylinder count into cubic inches and litres.
How this calculator works
CID = π × (bore ÷ 2)² × stroke × cylinders
Overboring raises displacement quickly because bore is squared. Taking a 4.00 inch bore out to 4.030 adds about 5 cubic inches across eight cylinders — the classic 350 to 355 conversion.
Worked example
With bore 4 in, stroke 3.48 in, number of cylinders 8 , this calculator returns 349.85 .
Displacement by bore size
Figures below assume stroke 3.48 in × number of cylinders 8 . Change any measurement in the calculator to get your own numbers.
| Bore | Displacement | Litres |
|---|---|---|
| 3 in | 196.8 | 3.22 |
| 3.5 in | 267.9 | 4.39 |
| 3.78 in | 312.4 | 5.12 |
| 4 in | 349.8 | 5.73 |
| 4.03 in | 355.1 | 5.82 |
| 4.25 in | 394.9 | 6.47 |
| 4.5 in | 442.8 | 7.26 |
An eight-cylinder engine with a 3.48 in stroke. Displacement scales with the square of the bore, so small bore changes matter more than they look.
Displacement of well-known engines
| Job | Size | Displacement |
|---|---|---|
| Small-block Chevy 350 | 4 in × 3.48 in × 8 | 349.8 |
| Chevy 350 bored 0.030 over | 4.03 in × 3.48 in × 8 | 355.1 |
| Ford 302 | 4 in × 3 in × 8 | 301.6 |
| Chrysler 440 | 4.32 in × 3.75 in × 8 | 439.7 |
| Chevy 454 big-block | 4.25 in × 4 in × 8 | 454.0 |
| Typical 2.0 L inline four | 3.39 in × 3.39 in × 4 | 122.4 |
Stroking an engine adds displacement faster than boring it, because stroke enters the formula linearly while bore is squared but limited by cylinder wall thickness.
Displacement unit conversions
| Type | Cubic inches | Notes |
|---|---|---|
| 1 litre | 61.02 | 1,000 cc |
| 2.0 L four-cylinder | 122.0 | The mainstream modern engine |
| 5.0 L V8 (302) | 305.0 | Ford Windsor, Coyote |
| 5.7 L V8 (350) | 350.0 | Small-block Chevrolet |
| 6.2 L V8 | 376.0 | LS3, modern GM |
| 7.4 L V8 (454) | 454.0 | Big-block Chevrolet |
To convert cubic inches to litres, divide by 61.024. To go the other way, multiply. Engine names round generously in both directions — a 350 is really 355 cubic inches once bored.
Frequently asked questions
How do you calculate cubic inches of an engine?
Multiply pi by the bore radius squared, by the stroke, by the number of cylinders. For a 4 in bore and 3.48 in stroke across eight cylinders that gives 350 cubic inches.
How much displacement does boring 0.030 over add?
About 5 cubic inches on a 350, taking it to roughly 355. Boring adds displacement with the square of the bore, but cylinder wall thickness limits how far you can go.
What does stroking an engine do?
A longer stroke adds displacement in direct proportion and raises torque at low rpm. It also raises piston speed, which is what ultimately limits how far a stroke can be taken.
Is bigger displacement always more power?
No. Displacement sets how much air an engine can move per revolution, but power depends just as much on how well it breathes, its compression ratio and how fast it can safely turn.
How do I convert cubic inches to litres?
Divide by 61.024. A 350 cubic inch engine is 5.73 litres, marketed as 5.7. A 454 is 7.44 litres, sold as 7.4.
Why is a 350 not exactly 5.7 litres?
Because 350 cubic inches is 5.735 litres, and manufacturers round to one decimal. Once bored 0.030 over it is nearer 355 cubic inches, or 5.8 litres, and still called a 350.
What is oversquare and undersquare?
Oversquare means the bore exceeds the stroke, which favours high rpm and peak power. Undersquare means a longer stroke than bore, which favours low-end torque. A 4 in bore with a 3.48 in stroke is oversquare.
How do I calculate engine displacement?
Multiply pi by the bore radius squared, by the stroke, by the number of cylinders. A 4.00 inch bore with a 3.48 inch stroke across eight cylinders gives 350 cubic inches.
How many cubic inches in a litre?
About 61.02. A 5.7 litre engine is roughly 350 cubic inches, and a 6.2 litre is about 376.
Does boring an engine add much displacement?
More than you might expect, because bore is squared in the formula. Going 0.030 inch over on a small-block V8 adds about 5 cubic inches, turning a 350 into a 355.
What is the difference between bore and stroke?
Bore is the cylinder diameter, stroke the distance the piston travels. A large bore with a short stroke revs higher and breathes better; a long stroke makes more low-end torque at the cost of piston speed.