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# Newton metre

The **newton metre** is a unit of torque (also called "moment") in the SI system. The symbolic form is **N m** or **N·m**.^{[1]} One newton metre, sometimes hyphenated *newton-metre*, is equal to the torque resulting from a force of one newton applied perpendicularly to a moment arm which is one metre long.

It is also used less commonly as a unit of work, or energy, in which case it is equivalent to the more common and standard SI unit of energy, the joule.^{[2]} In this very different usage the metre term represents the distance travelled or displacement in the direction of the force, and not the perpendicular distance from a fulcrum as it does when used to express torque. This usage is discouraged by the SI authority, since it can lead to confusion as to whether a given quantity expressed in newton metres is a torque or a quantity of energy. However, since torque represents energy transferred or expended per angle of revolution, one newton metre of torque is equivalent to one joule per radian.^{[3]}

Newton metres and joules are "dimensionally equivalent" in the sense that they have the same expression in SI base units:

- <math>1 \, \mathrm{N} \! \cdot \! \mathrm{m} = 1 \frac{\mathrm{kg} \, \mathrm{m}^2}{\mathrm{s}^2} \quad , \quad 1 \, \mathrm{J} = 1 \frac{\mathrm{kg} \, \mathrm{m}^2}{\mathrm{s}^2}</math>

Again, N⋅m and J are distinguished in order to avoid misunderstandings where a torque is mistaken for an energy or vice versa. Similar examples of "dimensionally equivalent" units include Pa versus J/m³, Bq versus Hz, and ohms versus ohms per square.

## Conversion factors

- 1 newton metre ≈ 0.7375621 pound-feet (often "foot-pounds")
- 1 kilogram-force metre = 9.80665 N·m
^{[4]}^{[5]} - 1 pound-foot (often "foot-pound") ≡ 1 pound-force-foot ≈ 1.3558 N·m
- 1 inch-ounce-force = 7.0615518 mN·m
- 1 dyne-centimetre = 10
^{−7}N·m - 1 joule = 1 N·m

## See also

## References

**^**BIPM - unit symbols**^**For example: Eshbach's handbook of engineering fundamentals - 10.4 Engineering Thermodynamics and Heat Transfer "In SI units the basic unit of energy is Newton-metre".**^**BIPM - special names**^***Mechanical Engineering Formulas Pocket Guide*, p6**^***Concise encyclopedia of plastics*, by Donald V. Rosato, Marlene G. Rosato, Dominick V. Rosato, p621