ENGINEERING CALCULATOR
Torque Calculator
A torque calculator computes torque from force and distance about a pivot: τ = F × r. Enter the applied force and the lever arm length, and the tool returns the torque in N·m, ft-lb, and in-lb at once. The full calculation is shown, so you can trace every number. It also works backwards, solving for the force you must pull, or the handle length you need, to reach a target torque. That is the same math behind a torque wrench, a lever, and a shaft drive.
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Free Online Tool
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Force × Distance Results
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Multiple Unit Outputs
Torque Calculator
Enter force and lever arm to calculate torque, or solve for force or arm length.
Torque
75 N·m
ft-lb
55.3 ft-lb
in-lb
663.8 in-lb
Formula
τ = F × r × sin θ
Engineering Calculator
Torque Calculator
Enter any two values — force, arm, or torque — and the tool computes the third.
Enter force
Enter arm length
Enter torque
Default 90° for perpendicular
Torque (N·m)
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Torque (ft-lb)
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Torque (in-lb)
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Torque (kgf·m)
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Formula
Enter values and press Calculate.
HOW IT WORKS
How to Use the Torque Calculator
Three steps produce the answer, and every step is visible. Choose what to solve for (torque, force, or arm length), enter the other two values, and read the result in all torque units instantly.
Torque Formula
τ = F × r
F = Applied Force (N)
r = Lever Arm Length (m)
General Form
τ = F × r × sin θ
Max torque at θ = 90°
Perpendicular force gives full torque
Worked Examples
Three common cases: solve for torque, force, or lever arm length. All results shown in multiple units.
250 N × 0.30 m
= 75 N·m
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20 ft·lb ÷ 2 ft
= 10 lbf
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75 ft·lb ÷ 125 lbf
= 0.6 ft (7.2 in)
Example 1 – Torque
75 N·m = 55.3 ft·lb = 664 in·lb
Example 2 – Force
10 lbf
Example 3 – Arm Length
0.6 ft (7.2 in)
Three Solve Modes
01
Solve for Torque
Enter force and arm length to get torque in N·m, ft·lb, and in·lb.
τ = F × r
02
Solve for Force
Enter target torque and arm length to find required force.
F = τ / r
03
Solve for Arm Length
Enter target torque and available force to determine handle length.
r = τ / FKey Concepts Clarified
Torque vs. Moment
Same physical quantity: force × distance. Used interchangeably; torque for rotation, moment for bending.
Torque vs. Work
Both in N·m, but torque is a vector (rotation), work is a scalar (energy). Torque × angle = work.
Lever Arm Effect
Longer arm multiplies torque with same effort — the principle behind the cheater bar.
MACHINE DESIGN APPLICATIONS
Torque vs. Bolt Torque vs. Motor Torque
Three different tools are all called torque calculators, and using the wrong one produces a wrong number. This page owns one of them and links the other two.
The lever-arm torque calculator answers "how hard, at what distance, does this turn." The bolt torque calculator answers "how much do I tighten this bolt to clamp the joint." The motor torque calculator answers "how much torque does this motor deliver at this RPM." They share a unit and a name, and almost nothing else.
Torque Calculator
Lever-arm torque: force applied at a distance. Calculates how hard, at what distance, a force turns about a pivot.
- Formula: τ = F × r
- Force × lever arm
- Torque wrench, lever, shaft drive
- This page
Bolt Torque Calculator
Tightening torque for a target clamp force on a fastener. Uses the nut factor K for friction in threaded joints.
- Formula: T = K × D × F
- Clamp force from torque
- Bolt tightening specs
- Linked from this page
Motor Torque Calculator
Shaft torque from motor power and speed. Converts between power, RPM, and torque for electric motors.
- Formula: T = P × 60 / (2π × RPM)
- Power × speed → torque
- Motor sizing
- Linked from this page
Torque Questions
Torque FAQ
Torque equals force times the perpendicular distance from the pivot to the line of action: τ = F × r. When the force is not perpendicular, use τ = F × r × sin θ, where θ is the angle between the force and the arm.
Multiply the applied force by the lever arm length, keeping units consistent. For a 250 N force at 0.30 m, torque is 250 × 0.30 = 75 N·m. To solve for force, divide torque by the arm; to solve for arm length, divide torque by the force.
The SI unit of torque is the newton-metre (N·m). Imperial and customary practice uses foot-pounds (ft-lb) and inch-pounds (in-lb), with 1 N·m = 0.7376 ft-lb = 8.851 in-lb.
None in the math. Torque and moment of force are the same quantity, the product of force and perpendicular distance. The word "torque" tends to describe turning a shaft or fastener; "moment" tends to describe bending. Both use τ = F × r.
No. Torque and work both use the unit N·m, but torque is a rotational vector quantity and work is a scalar energy transfer. Torque multiplied by the angle it turns through equals work.
Divide the target torque by the handle length: F = τ / r. For 120 N·m on a 0.30 m wrench, you need 400 N of pull at 90° to the handle.
Divide the target torque by the force you can apply: r = τ / F. For 75 ft-lb with a 125 lbf pull, you need a 0.6 ft, or 7.2 in, effective handle.
Yes, with the same force. Torque is force times arm length, so a longer handle produces proportionally more torque. That is why cheater bars work on stubborn fasteners.
The effective torque drops by sin θ. At 90° it is maximum, at 30° it is half, and pulling directly along the handle produces no torque at all. Always pull perpendicular to the handle.
Torque (τ = F × r) is the turning effect of a force at a distance. Bolt torque (T = K × D × F) converts a tightening torque into a target clamp force on a fastener, using the nut factor K for friction. Use the bolt torque calculator for fasteners.
Motor torque is the turning force a motor delivers on its shaft, computed from power and speed: T = P × 60 / (2π × RPM). It shares the unit with lever-arm torque but is a different calculation, handled by the motor torque calculator.
Multiply newton-metres by 0.73756. For example, 25 N·m is 25 × 0.7376 = 18.4 ft-lb. To convert the other way, multiply ft-lb by 1.35582.
PRECISION MANUFACTURING SUPPORT
From Torque Spec to Machined Part
This torque calculator gives you the spec. Now you need the part that applies it — whether a torque arm, lever boss, shaft with a keyway, or bracket with threaded holes. Machine it so the geometry matches the number.
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5‑axis CNC machining to ±0.001″
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50+ metals & plastics, ISO 9001 & AS9100
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Free DFM feedback, no minimum order