Free automotive calculators and tools for gear heads who love precision, performance, and fabrication. Calculate gear ratios, MPG, engine specs, and more.
Professional-grade calculators for enthusiasts, builders, tuners, and racers. No sign-up required, completely free to use.
Calculate engine RPM at any speed based on gear ratio, final drive, and tire diameter.
Calculate true fuel economy with corrections for gear ratio and tire size changes.
Calculate engine displacement from bore, stroke, and cylinder count.
Convert metric tire sizes to inches and calculate speedometer corrections.
Estimate quarter-mile elapsed time based on vehicle weight and horsepower.
Calculate required fuel injector size for your horsepower goal.
Whether you're building a race car, restoring a classic, or modifying your daily driver, accurate calculations are essential for success. Our calculators help you make informed decisions about parts selection, predict performance outcomes, and avoid costly mistakes.
All calculators on Gear Head Proving Grounds are 100% free with no registration required. No premium features locked behind paywalls—just straightforward tools that work.