Auto Racing
Calculator inputs
Enter your race-car data, then select Calculate.
Race Gear Ratio & Top Speed Calculator
Calculate speed in each gear, overall ratio, RPM after shifts, and drivetrain gearing for race-track setup.
Race setup results—Calculated from the values entered above.
1st gear overall ratio—
Top-gear speed (km/h)—
Formula
Speed (mph) = RPM × tire diameter ÷ (gear ratio × final drive × 336)
RPM after shift = shift RPM × next gear ratio ÷ current gear ratio
How to use it
Enter measured tire diameter, the differential/final-drive ratio, your intended shift or rev-limit RPM, and the transmission ratios. The table shows theoretical road speed in each gear and the RPM drop into the next gear.
Understanding the result
A shorter overall ratio increases torque multiplication but reduces theoretical speed for a given RPM. A taller ratio does the opposite. Compare the speed at the top of each gear with the speeds you actually reach at key points on the track.
Important: Racing setup is vehicle-, tire-, track-, and rules-dependent. Treat calculated values as planning targets, not guaranteed safe settings.
Motorsports Learning & Resources
Continue learning with engineering, sanctioning, safety, and race-technology resources.
National Motorsport AcademyOnline motorsport engineering degrees and industry-led training.Purdue Motorsports EngineeringMotorsports engineering education, projects, and career pathways.SAE International – Vehicle DynamicsEngineering fundamentals for acceleration, braking, handling, steering, and suspension.Formula SAEStudent race-car engineering competition information and technical resources.OptimumGVehicle dynamics education, software, seminars, and engineering resources.Racecar EngineeringTechnical motorsport articles covering race-car design and technology.SCCASports Car Club of America competition, events, rules, and driver resources.NASA Pro RacingNational Auto Sport Association racing, time trial, HPDE, and competition resources.FIAInternational motorsport regulations, safety, and technical information.High Performance AcademyPractical performance-car tuning, wiring, data, suspension, and motorsport training.