Engine Displacement Calculator
Enter the bore, stroke and number of cylinders to get engine size in cc, liters and cubic inches. Switch modes to find the bore or stroke you need for a target displacement, and work out the static compression ratio.
Compression ratio (uses the bore and stroke above)
Deck clearance is positive when the piston sits below the deck at top dead center. A dome reduces clearance volume, so enter it as a negative number.
How to use the Engine Displacement Calculator
- Choose the unit for bore and stroke: millimeters or inches.
- Enter the bore, stroke and number of cylinders from the spec sheet.
- Press Calculate to see displacement in cc, liters and cubic inches.
- Need a target size? Use Solve bore or Solve stroke and enter the displacement you want.
- Fill in the compression section with chamber, piston, gasket and deck figures to get the compression ratio.
Engine displacement formula
Displacement = π ÷ 4 × bore² × stroke × cylinders
- Bore and stroke in cm → result in cc (cm³). Divide by 1,000 for liters.
- Bore and stroke in inches → result in cubic inches. Multiply by 16.387064 for cc.
- Reverse: bore = √(4V ÷ (π × stroke × cylinders)) and stroke = 4V ÷ (π × bore² × cylinders).
Worked example: a V8 with a 4.00 in bore and a 3.48 in stroke: 0.7854 × 4.00² × 3.48 × 8 = 349.8 ci = 5,733 cc, the classic 350. Boring it 0.030 in over to 4.030 in gives 355.1 ci.
Compression ratio formula
CR = (Vs + Vc) ÷ Vc, where Vs is the swept volume of one cylinder and Vc is the clearance volume:
Vc = chamber cc + piston dish cc (− dome cc) + π ÷ 4 × gasket bore² × gasket thickness + π ÷ 4 × bore² × deck clearance.
Example: 86 × 86 mm cylinder (499.6 cc), 45 cc chamber, 3 cc dish, 87 mm × 0.8 mm gasket (4.76 cc) and 0.2 mm deck clearance (1.16 cc). Vc = 53.92 cc, so CR = (499.6 + 53.9) ÷ 53.9 = 10.27:1.
Bore and stroke of well-known engines
| Engine layout | Bore × stroke | Cylinders | Displacement |
|---|---|---|---|
| Square 2.0 inline-four | 86 × 86 mm | 4 | 1,998 cc |
| Oversquare 2.0 inline-four | 87.5 × 83.1 mm | 4 | 1,999 cc |
| Small 1.6 inline-four | 81 × 77.4 mm | 4 | 1,595 cc |
| 3.0 inline-six | 84 × 90 mm | 6 | 2,993 cc |
| 350 small-block V8 | 4.00 × 3.48 in | 8 | 349.8 ci / 5,733 cc |
| 6.0 V8 | 99 × 96.9 mm | 8 | 5,967 cc |
Frequently asked questions
How is engine displacement calculated?
Displacement = π ÷ 4 × bore² × stroke × number of cylinders. With bore and stroke in centimeters the answer is in cubic centimeters (cc). For example 8.6 cm × 8.6 cm × 4 cylinders gives 1,998 cc, sold as a 2.0 liter engine.
How do I convert cc to cubic inches?
Divide cc by 16.387, because one cubic inch is exactly 16.387064 cc. A 5,733 cc engine is 349.9 cubic inches, which is the famous 350 small-block.
What does oversquare mean?
An engine is oversquare when the bore is larger than the stroke (ratio above 1). Short strokes allow higher rpm. Undersquare engines have a longer stroke than bore and tend to make more low-end torque. A square engine has equal bore and stroke.
How do I calculate compression ratio?
Compression ratio = (swept volume + clearance volume) ÷ clearance volume, per cylinder. Clearance volume is the chamber volume plus the piston dish (minus a dome), the compressed head gasket volume and the deck clearance volume.
Why is my engine size different from the badge?
Manufacturers round displacement for marketing. A 1,998 cc engine is called 2.0 L and a 5,733 cc engine is sold as 5.7 L or 350 ci.
What is mean piston speed?
It is the average speed of the piston: 2 × stroke × rpm ÷ 60. Most road engines stay below about 20 m/s; race engines can exceed 25 m/s.