Torque Calculator
Compute torque from an applied force and lever arm radius.
Formula
T = F × r
Inputs
- Force (N)
- Lever arm (radius) (m)
What it does
Torque is a turning force: the force times the lever-arm distance, T = F × r.
Where it's used
Tightening bolts, wrench lengths, motor shafts and levers.
How to use it
- Enter the force in newtons.
- Enter the lever-arm length in metres.
- Read the torque in N·m.
The formula explained
- T
- torque, N·m
- F
- force at right angles to the arm, N
- r
- distance from the pivot, m
Worked example
Pushing 200 N on a 25 cm wrench.
Inputs:
- Force: 200 N
- Lever arm (radius): 0.25 m
The calculator gives:
- Result: 50 N·m
Tips and common mistakes
- Only the part of the force at right angles to the arm counts.
- A longer wrench gives the same torque with less force.
- Bolt torque specs are often in N·m or lb·ft (1 lb·ft ≈ 1.356 N·m).
Questions people ask
How do I convert between torque units?
1 N·m ≈ 0.738 lb·ft, 1 lb·ft ≈ 1.356 N·m, and 1 kgf·m ≈ 9.81 N·m. Bolt-tightening tables may use any of these, so check the unit before you set a torque wrench.
What if I don’t push at right angles to the wrench?
Only the perpendicular part of the force counts: T = F × r × sin θ. Pushing at 30° to the handle gives half the torque of pushing straight across it.
Why do bolt torque values matter so much?
Torque sets how hard the bolt clamps the joint. Too little and it can work loose; too much and it stretches or strips. Lubricated threads clamp harder for the same torque, so use the value for the condition (dry or oiled) the table states.
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Enter your values to get the result with the formula, substituted values and an explanation of each step.