Calculate torque from force and perpendicular distance to the pivot
Mechanical Calculator
Torque from power — Quick answer
Torque is the rotational equivalent of force. For a rotating shaft, torque is power divided by angular velocity.
T = P / ω = P × 60 / (2πN) (SI) T (N·m) = 9550 × kW / RPM T (lb-ft) = 5252 × HP / RPM
T — torque (N·m or lb-ft)
P — power (W or kW or HP)
ω — angular velocity (rad/s)
N — rotational speed (RPM)
Worked example: 5 kW motor at 1,500 RPM. T = 9,550 × 5 / 1,500 = 31.8 N·m. Convert: 31.8 N·m × 0.738 = 23.5 lb-ft. At 3,000 RPM the same 5 kW produces half the torque: 15.9 N·m.
Torque from power and speed (continuous duty)
Motor
RPM
Torque (N·m)
0.75 kW
1,500
4.8
1.5 kW
1,500
9.5
2.2 kW
1,500
14.0
5 kW
1,500
31.8
11 kW
1,500
70.0
22 kW
1,500
140
75 kW
1,500
477
5 kW
3,000
15.9
5 kW
750
63.7
Standard / source: ISO 80000-4 (mechanical quantities); IEC 60034-30-1 (motor efficiency / torque).
Used for: Motor selection for compressors / pumps / mills, gearbox sizing, bolt-tightening specs, shaft design (T = Jω'), drive-train analysis.
🔧 Torque Calculator
Formula
This calculator uses the standard torque calculator formula:
Torque Formula
τ = F × d × sin(θ)
Frequently Asked Questions
What is torque?⌄
Torque is the rotational equivalent of force. It measures how much a force causes an object to rotate about an axis. τ = F × d × sin(θ), measured in N·m or ft·lb.
What is the torque formula?⌄
τ = F × d × sin(θ), where F = applied force in newtons, d = perpendicular distance from the pivot in metres, and θ = angle between force and lever arm.
How do you convert N·m to ft·lb?⌄
1 N·m = 0.7376 ft·lb. To convert, multiply N·m by 0.7376. For example, 100 N·m = 73.76 ft·lb.
What is the difference between torque and moment?⌄
Torque and moment of force refer to the same concept. Torque is typically used in dynamics (rotating systems), while moment is used in statics (structural analysis).
How does lever arm length affect torque?⌄
Torque is directly proportional to lever arm length. Doubling the lever arm doubles the torque for the same applied force — this is the principle behind wrenches and levers.
What angle produces maximum torque?⌄
Maximum torque occurs when the force is applied perpendicular to the lever arm (θ = 90°), giving sin(90°) = 1. Any other angle reduces effective torque.
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