Small-engine & powersports calculators
WrenchMath is a set of rigorous, sourced calculators for people who work on small engines and powersport equipment. Every formula is pulled from engineering references or manufacturer specifications, implemented in Go, and machine-verified against an independent implementation before any page ships. The site is built by an engineer and has no advertising, no accounts, and no tracking cookies.
| Calculator | What it answers |
|---|---|
| 2-Stroke Premix Ratio | How much two-stroke oil to add to a given volume of gas at a given ratio |
| Density Altitude | Pressure altitude corrected for temperature: the altitude your engine's intake air "thinks" it is at |
| Sprocket & Gear Ratio | Drive ratio and output RPM from front and rear sprocket tooth counts |
| Go-Kart Gearing | Top speed, wheel RPM, and gear ratio for a go-kart drivetrain |
| Chain Length | Number of chain links required for a given sprocket pair and center distance |
| Compression Ratio | Compression ratio from bore, stroke, clearance volume, and deck/gasket dimensions |
| Jetting: Air-Density Correction | Directional main-jet correction (richer or leaner, in jet steps) when altitude or temperature changes from a known-good baseline |
| Tire Size & Speedometer | Actual vehicle speed and speedometer error from tire diameter and gear ratio |