Gear Ratio & Speed Calculator

Gear Ratio & Speed Calculator is an all-in-one drivetrain calculator and setup simulator designed for track enthusiasts, racers, off-road builders, and gearheads. Calculate exact relationships between engine RPM, vehicle speed, gear ratios, final drive, and tire sizes. Plan modifications and preview their impact before turning a single wrench. WHAT IF? VEHICLE SETUP SIMULATOR • Compare your current vehicle setup with a new What If? configuration side by side. • Evaluate changes in tire dimensions, final drive ratios, and transmission swaps. • Compare cruising RPM at 60, 80, 100, 120, and 130 km/h (or mph). • Check top speed and speed at specific RPM intervals (3,000 to redline). • Detailed gear-by-gear ratio and speed delta comparison. • Visual gear graph comparing current vs new setup curves. • Dedicated impact breakdown cards for tire size, final drive, and transmission changes. • Experiment freely without modifying your saved Garage vehicle profile. RPM & SPEED • RPM to Speed: Calculate true vehicle speed from engine RPM, selected gear, final drive, and tire dimensions. • Speed to RPM: Find required engine RPM for any target highway cruising speed. GEAR RATIO & FINAL DRIVE • Calculate overall drive ratio for each transmission gear. • Ring & pinion final drive swap analysis and ratio changes. GEAR SPEED • Full-spectrum speed table across all gears from 1,000 RPM up to engine redline. • Easily find shift points and maximum speed in each gear. TIRE SIZE & TIRE COMPARISON • Supports Metric tire sizes (e.g. 215/40R18, 265/70R17.5) and Flotation Inch sizes (e.g. 35x12.50R17). • Full decimal wheel diameter support including 17.5-inch wheels. • Side-by-side tire comparison: diameter, circumference, sidewall height, and speedometer error percentage. SHIFT RPM • Analyze engine RPM drop after upshifting from each gear. • Review step ratio percentages and gear spacing to keep engine in the powerband. TRANSMISSION PRESETS • Explore 74 transmission presets from manufacturers and performance applications. • Covers popular manual, automatic, and dual-clutch transmissions (TREMEC, ZF, Ford, GM, Toyota, Honda, Hyundai, BMW, Porsche, and more). • Quick 1-tap setup with realistic factory gear ratios. GARAGE • Save and manage multiple vehicle profiles with custom tire specs, final drives, and gear ratios. • Load any saved vehicle directly into the What If? simulator or individual calculators. SPROCKET / TOOTH COUNT • Motorcycle and chain-drive ratio calculator for front and rear sprockets. • Calculate sprocket tooth changes and target gearing. OFFLINE & UNIT SUPPORT • Instant calculations with zero latency — works completely offline without network connection. • Seamless 1-tap toggle between Metric (km/h, mm) and Imperial (mph, inches).