Gear Ratio to Torque Calculator
Convert input torque to output torque based on gear ratios. Essential tool for mechanical design, automotive engineering, and power transmission calculations.
Torque Parameters
Torque available at the input shaft
Ratio between input and output gears (e.g., 4:1 = 4)
Calculation Results
Enter torque parameters and click "Calculate Output Torque" to see results
Engineering Note
These calculations provide theoretical torque values. Actual output may vary due to bearing friction, lubrication conditions, and manufacturing tolerances.
Gear Ratio to Torque Explained Simply
A gear ratio to torque relationship explains how gears multiply rotational force. When you trade speed for torque through gearing, the output torque becomes higher than the input. This fundamental principle powers everything from car transmissions to industrial machinery.
Think of it like a bicycle - when you shift to a lower gear, you can climb hills more easily because the torque at the wheels increases. The same principle applies to any geared system where mechanical advantage is needed.
This calculator helps you determine exactly how much torque multiplication you'll get from any gear ratio, making design decisions much clearer.
How Gear Ratio Affects Torque
A gear ratio compares the rotational speeds of two connected gears. A higher ratio means the output gear turns slower than the input gear, but with proportionally more torque.
For example, a 5:1 gear ratio means the output shaft turns at 1/5 the speed of the input shaft, but delivers 5 times the torque. This trade-off between speed and torque is the foundation of all geared power transmission.
The exact torque multiplication depends on the gear ratio and any efficiency losses in the system, which this calculator accounts for automatically.
Formula Used in the Calculator
Torque Conversion Formulas
Basic Torque: Output Torque = Input Torque × Gear Ratio
With Efficiency: Output Torque = Input Torque × Gear Ratio × (Efficiency ÷ 100)
From Teeth: Gear Ratio = Driven Teeth ÷ Driving Teeth
Where:
- Input Torque = Torque available at the input shaft
- Gear Ratio = Speed reduction ratio (output speed ÷ input speed)
- Efficiency = Mechanical efficiency percentage (typically 85-95%)
- Teeth = Number of teeth on driving/driven gears
The calculator automatically handles unit conversions and applies efficiency factors when specified.
Unit Flexibility
The calculator supports three common torque units to accommodate different engineering standards and applications:
Newton-meters (Nm)
SI unit, commonly used in metric engineering and European standards.
Pound-feet (lb-ft)
Imperial unit, widely used in American automotive and machinery design.
Pound-inches (lb-in)
Small-scale unit, common in precision instruments and small machinery.
Units can be mixed - input in one unit, output in another - with automatic conversion for your convenience.
Example Calculation
Automotive Drivetrain Example
| Parameter | Value |
|---|---|
| Input Torque | 100 Nm |
| Gear Ratio | 4:1 (4.0) |
| Efficiency | 90% |
| Output Torque | 360 Nm |
Interpretation
The 4:1 gear ratio multiplies the input torque by 4, but with 90% efficiency, the actual output is 360 Nm. This represents a 3.6x increase in available torque, allowing the vehicle to handle heavier loads or climb steeper grades.
Final Thoughts
Torque conversion should not require complex unit conversions or manual calculations. The Gear Ratio to Torque Calculator delivers fast, accurate results across multiple unit systems while accounting for real-world efficiency losses.
Whether you're designing a car transmission, sizing a robotic actuator, or analyzing an industrial drive system, this tool ensures you understand exactly how gear ratios affect torque multiplication. Make confident design decisions with reliable torque calculations.