Tools / 01
Gear ratio calculator.
Your chassis. Your parts. Your gearing.
Start with the chassis.
Choose the code you know. Start with stock, pick a mapped swap, or build a combination of your own.
Engine, transmission, differential, tires. Every part stays connected to your build.
Build your setup
1 / 5Choose your chassis
Built for the drive.
Product spotlight
Compare setups
Two transmissions. One chart. See exactly what changes.
03 / ExploreFind the missing ratio
Work backward from speed, RPM, or tire size.
04 / ExploreStart with a vehicle
Explore reference setups before building your own.
A little context
Understand the numbers.
Transmission, final drive, and tire size all shape how a car feels. Get familiar with the relationships.
Explore the guidesWhat does a gear ratio calculator do?
A gear ratio calculator shows how transmission ratios, final drive, tire size, and engine RPM combine to determine vehicle speed in each gear.
How does final drive affect RPM and speed?
A shorter final drive multiplies every gear more aggressively, which improves acceleration but raises RPM at a given speed. A taller final drive does the opposite.
Does tire size change effective gearing?
Yes. A taller tire covers more ground per revolution, which effectively makes the setup taller and lowers engine RPM at the same road speed.
Can I compare two transmissions side by side?
Yes. The comparison tool overlays two RPM vs speed maps so you can see top-speed, cruise RPM, and gear-spacing differences clearly.