Free, accurate automotive calculators - built by enthusiasts, for enthusiasts.
TunerBench is a collection of free calculators for people who work on cars - from checking whether a new wheel and tire setup will throw off your speedometer to sizing fuel injectors for a turbo build. Every tool runs instantly in your browser, works on your phone in the garage, and never asks you to sign up for anything.
Every formula on this site comes from established engineering references - SAE standards, factory service documentation, and the same math used by drivetrain and fuel-system engineers. We verify each calculator against known reference values before publishing it. Where real-world behavior differs from theory (tire deflection, drivetrain losses, BSFC variation), the explainer below each calculator says so explicitly.
TunerBench is built and maintained by automotive enthusiasts with years of hands-on experience in the BMW and Porsche performance world - building, tuning, and documenting cars for one of the largest automotive enthusiast audiences online.
Missing a tool you need? Found a number that looks off? We genuinely want to hear about it - reach out at [email protected].
These calculators are provided for informational purposes. Always verify critical specifications (fuel system sizing, compression ratios, tire fitment) with your tuner, engine builder, or vehicle manufacturer before making changes. Modifying a vehicle can affect safety, emissions compliance, and warranty coverage.