Gear Ratio Calculator
Calculate gear ratios using either the number of gear teeth or engine RPM, tire diameter, and vehicle speed. Select the calculation method, input values, choose units, and view results in standard, step-by-step, or chart views.
Result
Calculation Steps
Gear Ratio Visualization
Formulas
Gear Ratio Calculations
Gear ratios can be calculated using the following methods:
1. Number of Gear Teeth
Where:
- GR: Gear Ratio
- T₂: Number of teeth on driven (output) gear
- T₁: Number of teeth on driving (input) gear
2. Engine RPM, Tire Diameter, and Speed
Where (Imperial):
- GR: Gear Ratio
- RPM: Engine revolutions per minute
- D: Tire diameter (inches)
- S: Vehicle speed (mph)
- FD: Final drive ratio (assumed 1 if unknown)
- 63360: Inches per mile
Metric Formula:
Where (Metric):
- D: Tire diameter (cm)
- S: Vehicle speed (km/h)
- 100000: cm per km
Usage Notes:
- Inputs must be positive numbers.
- Results are rounded to 3 decimal places.
- Final drive ratio is assumed to be 1 unless specified.
How to Use the Gear Ratio Calculator
- Select Method: Choose between gear teeth or RPM-based calculation.
- Input Values: Enter the required values (teeth count or RPM, tire diameter, speed).
- Select Units: For RPM method, choose imperial or metric units.
- Choose Display: Select standard, step-by-step, or chart view.
- Calculate: Click “Calculate” to process inputs.
- View Results: Review the gear ratio and visualizations.
- Reset: Click “Reset” to clear fields.
Frequently Asked Questions (FAQs)
What is a gear ratio?
The gear ratio is the ratio of the number of teeth on the driven (output) gear to the driving (input) gear, or the relationship between engine RPM, tire size, and vehicle speed. It determines torque and speed output.
How is gear ratio calculated from gear teeth?
Divide the number of teeth on the driven gear (T₂) by the number of teeth on the driving gear (T₁): GR = T₂ ÷ T₁.
How is gear ratio calculated from RPM and speed?
Use the formula GR = (RPM × π × D × 60) ÷ (S × 63360 × FD) for imperial units, or GR = (RPM × π × D × 60) ÷ (S × 100000 × FD) for metric units, where D is tire diameter, S is speed, and FD is final drive ratio.
What is the financial gearing ratio?
The financial gearing ratio measures a company’s debt relative to its equity, calculated as Debt ÷ Equity, often expressed as a percentage by multiplying by 100. It’s unrelated to mechanical gear ratios.
What are the 7 types of gears?
The seven common types of gears are: Spur, Helical, Bevel, Worm, Planetary, Rack and Pinion, and Internal gears. Each has specific applications based on torque, speed, and orientation needs.