Calculator Inputs
Use one method at a time. The result appears above this form after submission.
Formula Used
1) Force and radius method
T = F × r × sin(θ)
Torque equals applied force times radius times the sine of the included angle.
2) Power and speed method
T = P / ω and ω = 2πN / 60
Torque is power divided by angular speed. Use this method for motors, drives, and rotating machines.
3) Tangential force and diameter method
T = Ft × d / 2
Torque equals tangential force multiplied by half the diameter. This suits pulleys, wheels, and drums.
4) Inertia and angular acceleration method
T = I × α
Torque equals mass moment of inertia times angular acceleration. This helps with startup and acceleration torque studies.
Design Torque: Tdesign = Tbase × Service Factor
Estimated Output Torque: Tout = Tdesign × Gear Ratio × Efficiency
How to Use This Calculator
- Select the method that matches your known engineering inputs.
- Enter the values and choose the correct units.
- Add service factor, efficiency, and gear ratio if needed.
- Choose the preferred output unit for display.
- Press Calculate Torque to see the result above the form, view the graph, and export the report.
Example Data Table
| Case | Method | Inputs | Torque |
|---|---|---|---|
| Motor shaft sizing | Power × Speed | 15 kW, 1450 RPM | 98.79 N·m |
| Lever arm loading | Force × Radius × Angle | 450 N, 0.22 m, 90° | 99.00 N·m |
| Pulley rim load | Tangential Force × Diameter | 1800 N, 0.12 m | 108.00 N·m |
| Startup acceleration | Inertia × Angular Acceleration | 3.5 kg·m², 18 rad/s² | 63.00 N·m |
FAQs
1. What is rotating torque?
Rotating torque is the turning effect produced by force around an axis. It determines how strongly a shaft, wheel, gear, or motor can rotate a load.
2. Which method should I choose?
Choose the method that matches your known inputs. Use force-radius-angle for levers, power-speed for motors, tangential force-diameter for pulleys, and inertia-acceleration for startup studies.
3. Why does the angle matter?
Only the force component perpendicular to the radius produces torque. A 90 degree angle gives maximum torque, while a zero degree angle gives no turning effect.
4. Can I use imperial and metric units together?
Yes. The calculator converts the entered values into base units internally, then returns torque in your preferred unit. This helps compare systems without manual conversions.
5. What does service factor do?
Service factor increases the calculated torque to reflect shock, overload, or uncertain duty. It is a design margin, not a replacement for full engineering validation.
6. How does gear ratio affect torque?
A higher reduction ratio usually increases output torque while reducing speed. This page estimates output torque by applying gear ratio and efficiency to the design torque.
7. Why does torque drop when speed rises at constant power?
For constant power, torque and angular speed are inversely related. When speed increases, the available torque decreases because the same power is spread across faster rotation.
8. Is this calculator enough for final mechanical design?
It is excellent for estimation and quick checks. Final design should also consider fatigue, misalignment, peak loads, thermal limits, material strength, bearings, and applicable design standards.