Gear Ratio Calculator 2026
Calculate exact gear ratios, output RPM, and torque multipliers. Instantly evaluate mechanical advantage for automotive drivetrains, industrial machinery, and robotics based on driver and driven gear teeth.
Drivetrain Configuration
Define gear teeth count and input shaft speed
The number of teeth on the input gear connected to the power source
The number of teeth on the output gear receiving the power
Revolutions per minute of the driver gear (e.g., engine or motor speed)
Mechanical Profile
Kinematic Breakdown & Torque Analysis
Configure your driver and driven gear teeth, then click Calculate Ratio to inspect your mechanical advantage.
Ratio Applications
Standard gear ratio classifications and their typical mechanical applications in automotive and industrial settings.
| Gear Ratio | Classification | Typical Application |
|---|---|---|
| < 1:1 | Overdrive | High-speed cruising, fuel efficiency, low-load applications. |
| 1:1 | Direct Drive | Equal speed and torque transfer, direct power coupling. |
| 2:1 – 3:1 | Standard Reduction | Balanced torque and speed, general machinery, automotive cruising. |
| 4:1 – 6:1 | Heavy Reduction | Towing, off-roading, heavy lifting, high-torque requirements. |
| 10:1+ | Extreme Reduction | Winches, cranes, conveyor belts, maximum torque at very low speeds. |
Mechanical Advantage FAQ
Learn more about gear ratios, torque multiplication, and how drivetrain configurations affect performance.
A gear ratio is the ratio of the number of teeth on the driven gear to the number of teeth on the driver gear. It determines the mechanical advantage, defining how much torque is multiplied and how speed is reduced or increased between the input and output shafts.
Gear ratio is calculated by dividing the number of teeth on the driven (output) gear by the number of teeth on the driver (input) gear. Alternatively, it can be calculated by dividing the input RPM by the output RPM.
Gear ratio inversely affects speed and torque. A higher gear ratio (greater than 1:1) reduces output speed but multiplies torque, ideal for heavy loads. A lower gear ratio (less than 1:1) increases output speed but reduces torque, ideal for high-speed applications.
A reduction gear has a ratio greater than 1:1, meaning the output shaft spins slower than the input shaft but with increased torque. An overdrive gear has a ratio less than 1:1, meaning the output shaft spins faster than the input shaft but with decreased torque.
No, ideal gear ratios do not change horsepower. Horsepower is the rate at which work is done. While gears multiply torque, they proportionally reduce speed (or vice versa), keeping the theoretical horsepower constant. In reality, a small amount of horsepower is lost to friction and heat in the gear train.