Calculate vehicle speed at any RPM based on transmission gear ratios, rear end ratio, and tire diameter. Essential for optimizing shift points and gear selection.
This gear ratio calculator helps drag racers determine optimal shift points, predict finish line speeds, and analyze transmission performance. Input your transmission ratios, rear gear ratio, tire size, and target RPM to calculate exact vehicle speed.
Understanding gear ratios is crucial for drag racing success. The calculator uses the formula: MPH = (RPM × Tire Diameter) ÷ (Gear Ratio × Rear Ratio × 336) to provide precise speed calculations for each gear.
Proper gear ratio selection determines whether your vehicle finishes the quarter mile in the optimal gear. Too short gears cause over-revving, while too tall gears prevent reaching peak power RPM. Our drag racing calculator analyzes your complete drivetrain to recommend ideal shift points.
The calculator supports popular transmissions including Powerglide, TH350, TH400, modern multi-speed automatics, and manual transmissions. Factor in converter slip for automatic transmissions to get accurate trap RPM predictions.