Torque Calculator
Rigid lever: τ = F × r × sin(θ); optional mechanical power P = τ × 2π × RPM / 60 in watts. Enter force, not mass. No fastener preload or design approval. Steady shaft model: ω = 2π × RPM / 60; T = 1000 × P(kW) / ω. Use mechanical output power and speed at the same shaft. No electrical efficiency, gearbox losses, starting torque or stall torque is inferred.
A QUICK WALKTHROUGH
How to use this tool
- Force and lever arm: Force (N), Lever arm (m), Angle (°), Speed (RPM, optional).
- Shaft power and speed: Shaft output power (kW), Shaft speed (RPM). Enter 1–20 positive speeds, one per line. The same entered power applies to every row; these are your scenarios, not rated motor speeds.
- Full calculation report: Arithmetic uses JavaScript Number (binary64). Display: at most 8 significant digits. Report: actual JavaScript numeric values, not exact decimal arithmetic. Inputs, formulas, units and all scenario rows are included.
Rigid-lever arithmetic
The calculator uses τ = F × r × sin(θ), where force is in newtons, lever arm is in metres, and θ is the angle between the force and the lever arm. The result is torque in N·m.
Optional mechanical power
When RPM is entered, mechanical power is calculated as P = τ × 2π × RPM / 60 in watts. This is ideal mechanical power from the calculated torque and speed.
Calculation scope
Use force, not mass. This tool performs bounded arithmetic for a rigid lever; it does not calculate fastener preload or approve an engineering design.
Force and lever arm
F = 100 N, r = 0.5 m, θ = 90°, RPM = 120 → Torque = 50 N·m; power ≈ 628.32 W. τ = 100 × 0.5 × sin(90°) = 50 N·m; P = τ × 2π × 120 / 60.
Shaft power and speed
Steady shaft model: ω = 2π × RPM / 60; T = 1000 × P(kW) / ω. Use mechanical output power and speed at the same shaft. No electrical efficiency, gearbox losses, starting torque or stall torque is inferred.
Constant-power comparison
Enter 1–20 positive speeds, one per line. The same entered power applies to every row; these are your scenarios, not rated motor speeds.
Full calculation report
Units: 1 lbf = 4.4482216152605 N; 1 ft = 0.3048 m; 1 lb·ft = 1.3558179483314004 N·m. Divide N·m by this factor to obtain lb·ft. Arithmetic uses JavaScript Number (binary64). Display: at most 8 significant digits. Report: actual JavaScript numeric values, not exact decimal arithmetic. Inputs, formulas, units and all scenario rows are included.
GOOD TO KNOW
Common questions
What angle should I enter?
Enter the angle between the lever arm direction and the applied force, from 0° to 180°.
Can I enter a mass instead of force?
No. Enter force in newtons. Convert a mass to force using the assumptions appropriate to your situation before using this calculator.
When is power shown?
Power is shown only when RPM is supplied. It uses the torque result and P = τ × 2π × RPM / 60.
Can this calculate stall torque or gearbox output?
Steady shaft model: ω = 2π × RPM / 60; T = 1000 × P(kW) / ω. Use mechanical output power and speed at the same shaft. No electrical efficiency, gearbox losses, starting torque or stall torque is inferred.
What is included in the report?
Arithmetic uses JavaScript Number (binary64). Display: at most 8 significant digits. Report: actual JavaScript numeric values, not exact decimal arithmetic. Inputs, formulas, units and all scenario rows are included.