Calculator inputs
Choose a torque method, enter values, then review the live engineering summary. The radius field acts as arm length or reference radius.
Plotly graph
The curve updates after calculation to show how torque changes with arm length, speed, or preload.
Example data table
| Case | Method | Key Inputs | Base Torque | Design Torque |
|---|---|---|---|---|
| Servo arm check | Force and arm length | 220 N, 0.18 m, 90°, 90% efficiency, SF 1.25 | 39.60 N·m | 55.00 N·m |
| Motor sizing | Power and shaft speed | 5.5 kW, 960 RPM, 92% efficiency, SF 1.30 | 54.72 N·m | 77.25 N·m |
| Fastener installation | Tightening torque from preload | K=0.20, 24 kN preload, 16 mm diameter, 88% efficiency, SF 1.10 | 76.80 N·m | 96.00 N·m |
Formula used
Force and arm length
T = F × r × sin(θ)
Use this when a force acts at a known distance from the axis. The angle term handles nonperpendicular loading.
Power and speed
T = P / ω, where ω = 2πN / 60
Use this method for rotating shafts, motors, gearboxes, and power transmission checks when speed is known.
Tightening torque
T = K × Fp × d
Use this estimate for fastener installation. K reflects thread and bearing friction, lubrication, and surface condition.
How to use this calculator
- Select the calculation method that matches your engineering case.
- Enter the required inputs and choose the correct units.
- Add efficiency and service factor to reflect realistic operating conditions.
- Press Calculate torque to show the results above the form.
- Review base torque, design torque, tangential force, equivalent power, and the graph.
- Export the calculated summary using the CSV or PDF buttons.
FAQs
1. What does this RC torque calculator estimate?
It estimates torque for three common engineering cases: force on a lever arm, power at a shaft speed, and tightening torque from preload and diameter.
2. Why is design torque higher than base torque?
Design torque includes service factor and efficiency losses. That makes the result more suitable for sizing parts, selecting motors, and checking realistic operating demand.
3. When should I use the force and arm method?
Use it when a known force acts at a measured distance from the center of rotation, such as handles, brackets, links, wrench arms, or servo horns.
4. When should I use the power and speed method?
Use it for motors, drives, shafts, fans, and rotating machinery when power and RPM are known or when you need torque from an operating point.
5. Is the tightening torque result exact?
No. Tightening torque is an estimate because friction changes with lubrication, finish, coatings, and joint condition. Use project standards or validated test data when accuracy matters.
6. What angle should I enter for a perpendicular force?
Enter 90 degrees. At that angle, the full force contributes to torque because the sine term becomes one and the moment arm is fully effective.
7. Why does torque drop as RPM increases?
For a fixed power level, torque and speed move inversely. Higher speed means the same power is delivered with less torque.
8. Can I export the results for reports?
Yes. After calculation, use the built-in CSV and PDF buttons to save a compact summary of the result metrics for documentation or review.