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Engine & Maintenance

Compression Ratio Calculator

Static CR from bore, stroke, head chamber, piston dome/dish, deck height, and head-gasket volume.

Inputs

Positive = piston below deck

Results
Live

  • Static compression ratio

    16.42:1

  • Swept volume

    449.49cc

  • Clearance volume

    29.14cc

  • Gasket volume

    3.69cc

  • Deck volume

    1.45cc

Formula

CR = (swept + clearance) / clearance

Positive piston volume is a dome (raises CR). Negative is a dish (lowers CR).

Related calculators

Engine Displacement
Swept volume from bore, stroke, and cylinder count. Output in cc, liters, and cubic inches.
2-Stroke / 4-Stroke Displacement
Same swept volume math, plus a power-stroke comparison: a two-stroke fires every crank revolution, a four-stroke every other rev.
Bore & Stroke
Solve the missing dimension. Leave bore at 0 to find bore from displacement and stroke, or stroke at 0 to find stroke from bore.
Piston Displacement
Swept volume of one piston, plus mean piston speed at a chosen RPM. High mean piston speed is a durability red flag.