Compression Ratio Calculator

Calculate static compression ratio from cylinder dimensions.

Typical: 58-76cc for most heads
Negative for dish, positive for dome
Piston below deck surface

Typical Compression Ratios

ApplicationRatioFuel
Economy Engine9.0-10.5:187 Octane
Performance Street10.5-11.5:191-93 Octane
Race Engine (NA)12.0-14.0:1Race Gas
Turbo/Supercharged8.0-9.5:191+ Octane
Diesel14.0-23.0:1Diesel