What is a Torque Calculator?
The torque calculator computes torque (rotational force) from force and distance from the pivot, and converts between units like N·m and kgf·m. It is used for bolt tightening and motor specs.
How it's calculated
Torque T = force F × distance r (units: N·m)
1 kgf·m ≈ 9.807 N·m
Variable definitions
| Variable | Meaning | Unit |
|---|---|---|
| T | Torque | N·m |
| F | Applied force | N |
| r | Distance from pivot | m |
Assumptions
This assumes the force is applied perpendicular to the lever arm. If the force is angled relative to the arm, actual torque becomes T=F×r×sinθ — smaller than the simple formula, which is exactly why turning a wrench at an angle feels weaker.
Worked example
A 0.3m wrench with 200N of force applied perpendicular to it
- T = 200 × 0.3 = 60 N·m
- In kgf·m: 60÷9.807 ≈ 6.1 kgf·m
Torque vs. horsepower — what's the difference?
Torque measures how hard something rotates; horsepower (power output) measures how fast that force can do work.
Power = torque × rotational speed
Torque is closely tied to acceleration and towing power, while horsepower relates more to top speed. Electric motors deliver maximum torque at 0 RPM, which is why electric vehicles feel so quick off the line.
Good to know
- Door handles are placed opposite the hinge because of torque — the farther from the pivot, the more rotational force the same push generates.
- A longer wrench loosens a bolt more easily, but over-tightening can stretch and damage the bolt, which is why specifications list exact torque values for critical fasteners.
- The real goal of tightening a bolt is to create clamping force between the parts — torque is just the indirect means of producing it, which is why lubricated threads produce more clamping force at the same torque.
- N·m and Joules share the same unit components but are different physical quantities. Torque produces rotation; Joules measure energy.
- One horsepower (HP) was defined by James Watt based on the sustained work output of a horse, back when he needed a way to explain steam engine capacity to customers.
Frequently asked questions
Q. How do I convert kgf·m to N·m?
Multiply by 9.807. 10 kgf·m is about 98.1 N·m.
Q. Does higher torque always mean faster?
No. Torque affects acceleration and towing capacity more; horsepower affects top speed more.
Q. What happens if I over-tighten a bolt beyond spec?
The bolt can deform plastically or fracture, and thread damage can actually reduce the clamping force.