Gear Ratio Calculator
Find gear ratio and output speed.
Gear ratio sets the trade-off between speed and torque.
How the Math Works
The gear ratio is calculated by dividing the number of teeth on the driven gear by the number of teeth on the driver gear. This ratio tells you how many times the driven gear will rotate for each rotation of the driver gear. For example, if the driver gear has 10 teeth and the driven gear has 30 teeth, the ratio is 3:1, meaning the driven gear turns once for every three rotations of the driver. The formula can also be rearranged to solve for missing values, such as determining the number of teeth needed on the driven gear to achieve a specific ratio or calculating the output speed by dividing the input speed by the gear ratio.
Practical Applications
To use this calculator, first identify the number of teeth on both the driver and driven gears in a mechanical system. Input these values to determine the gear ratio, which helps in selecting appropriate gears for a specific application. For instance, in a bicycle, a higher gear ratio (e.g., 4:1) provides more torque for climbing hills but reduces speed, while a lower ratio (e.g., 1:3) increases speed on flat terrain. Additionally, if you know the input speed (e.g., 300 RPM from a motor), dividing it by the gear ratio yields the output speed (e.g., 75 RPM for a 4:1 ratio), allowing you to optimize performance based on torque and speed requirements.
Day-to-Day Use
Understanding gear ratios helps in everyday scenarios like adjusting bicycle gears for efficiency on different terrains, selecting the right gear in a car's transmission for fuel economy, or even in household appliances like washing machines, where gear ratios control agitation speed. For example, using a lower gear ratio when cycling uphill reduces effort but slows speed, while a higher ratio on flat roads maximizes speed. This knowledge empowers users to make informed decisions about mechanical systems, improving performance, reducing energy consumption, and extending equipment lifespan by avoiding unnecessary strain from mismatched gear ratios.
Worked example
40/20 = 2:1 → 1000 RPM in, 500 RPM out.
FAQ
Torque?
Output torque = input torque × ratio (ignoring losses).