Last updated: November 18, 2025
N·m vs joules explained
In the SI, one newton-meter equals one joule. The Nm to Joules Calculator leverages that identity to translate torque-style values into energy (and back) while still allowing pound-feet or pound-inches for teams who prefer imperial units.
How the conversion works
Work equals force times displacement, and torque equals force times lever arm. When the displacement and lever arm are expressed in meters with forces in newtons, both evaluate to joules:
To convert to imperial torque units, multiply or divide by .
Units and conversions
| Unit | Relation |
|---|---|
| Joule (J) | Base SI energy |
| Newton-meter (N·m) | Identical magnitude to joule |
| Kilojoule (kJ) | |
| Pound-foot (lb·ft) | |
| Pound-inch (lb·in) |
Worked examples
- Energy perspective on torque
A gearbox delivers 45 N·m. Express that as joules per radian of rotation.
Result: every radian of motion stores or releases 45 J.
- Converting joules to lb·ft
A flywheel stores 750 J. Express that energy as an equivalent pound-foot value.
Result: the flywheel’s energy matches 553 lb·ft of torque through one radian.
Tips and pitfalls
- Equal units do not mean equal physical meaning: torque is vectorial (it has direction), whereas energy is scalar. Convert only when you need numerical magnitude comparisons.
- When documenting work done over a full rotation, multiply torque by angular displacement in radians to avoid confusing torque with energy outright.
- Imperial “foot-pounds” in ballistics texts refer to energy, while “pound-feet” in mechanical texts refer to torque; spelling them out prevents ambiguity.
- Keep radians in your calculations; mixing degrees into torque × angle integrations introduces a hidden conversion factor of .