Physics
Torque Calculator
Calculate effective torque, mechanical power, work per revolution, and the effect of lever length. The guide explains moment arms, force angle, RPM conversion, sign direction, and why a static result does not establish shaft or fastener safety.
Calculated torque-
Mechanical power-
Mechanical power-
Work per revolution-
Decision view
Lever arm, effective force, and rotation
Lever arm, effective force, and rotationThe force arrow acts at the entered radius from the pivot; the perpendicular-force fraction determines the displayed torque and rotational power.
Exact scenario comparisonLever arm length (m) changes while all other entered assumptions remain constant.
| Lever arm length (m) | Calculated torque | Mechanical power | Mechanical power | Work per revolution |
|---|
How to use Torque Calculator
- Enter the applied force, pivot-to-force lever length, and the percentage acting perpendicular to the lever.
- Confirm that the diagram's force direction and moment arm match the physical setup.
- Use RPM only when calculating steady rotational power; evaluate transient and peak loads separately.
Calculator guide
Understanding Torque Calculator
Torque depends on force, lever arm, and the perpendicular component of that force. The page separates those ingredients and connects static torque to rotational power only after rotational speed is entered.
Calculation method
How the calculation works
Multiply force by the perpendicular lever arm to obtain torque and combine torque with rotational speed for mechanical power. Torque T = F × r × effective fraction. Angular speed ω = RPM × 2π/60, power P = Tω, and ideal work per revolution equals T × 2π.
Geometry check
Force, radius, and line of action
Three equivalent descriptions can verify the same torque.
A force aimed directly toward the pivot has zero moment even when its magnitude is large.
Worked situations
Practical examples
- A 450 N force at 0.35 m with full perpendicular effectiveness produces 157.5 N·m.
- At 900 rpm, that steady torque corresponds to about 14.84 kW ideal mechanical power.
- Work per complete revolution is approximately 989.6 joules.
Better inputs
Useful tips
- Measure the perpendicular moment arm, not merely the straight-line distance to the force application point.
- Use peak or duty-cycle torque when selecting shafts, couplings, motors, and gearboxes.
- Keep clockwise and counterclockwise sign conventions consistent when combining several torques.
Before relying on the result
Limitations and common mistakes
- The calculation omits inertia, acceleration, impact, vibration, friction, and drivetrain efficiency.
- Lever or shaft strength, stress concentration, keys, splines, fasteners, fatigue, and guarding are not checked.
- A percentage input approximates perpendicular force but does not reconstruct the actual force angle or geometry.
Reference
Key terms
- Torque
- Rotational moment of a force about an axis.
- Moment arm
- Perpendicular distance from the axis to the force line of action.
- Angular speed
- Rate of rotation expressed in radians per second.
- Work per revolution
- Ideal energy transferred by constant torque through one full turn.
Important note
Calculated from the entered values using the displayed physical model. Confirm that its assumptions, units, boundary conditions, and safety limits match the application.
Frequently asked questions
What does 50% effective force mean?
It models a perpendicular component equal to half the entered force, equivalent to a sine factor of 0.5.
Is torque the same as work?
No. Both share force-distance dimensions, but work depends on displacement while torque is a rotational moment.
Why can torque be high while power is low?
Power is torque multiplied by angular speed; high torque at very low speed can transfer little power per second.
Can I use this for tightening a bolt?
It can calculate applied moment, but clamp load depends on thread geometry, friction, lubrication, and joint conditions.