# Newton metre

The newton metre (also newton-metre, symbol Nm,[1] N m[1]) is a unit of torque (also called moment) in the SI system. One newton metre is equal to the torque resulting from a force of one newton applied perpendicularly to the end of a moment arm that is one metre long. The nonstandard symbol Nm occurs in some fields.

Newton metre
One newton-metre is the torque resulting from a force of one newton applied perpendicularly to the end of a moment arm that is one metre long.
General information
Unit systemSI derived unit
Unit oftorque
SymbolNmorN m
Conversions
1 Nm in ...... is equal to ...
FPS system   0.73756215 ft lbf
inchpound-force   8.8507 in lbf
inchounce-force   141.6 in oz

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 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 generally discouraged,[3] since it can lead to confusion as to whether a given quantity expressed in newton metres is a torque or a quantity of energy.[4] However, since torque represents energy transferred or expended per angle of revolution, one newton metre of torque is equivalent to one joule per radian.[4]

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

${\displaystyle 1\,{\text{N}}{\cdot }\mathrm {m} =1{\frac {{\text{kg}}{\cdot }{\text{m}}^{2}}{{\text{s}}^{2}}}\quad ,\quad 1\,\mathrm {J} =1{\frac {\mathrm {kg} {\cdot }\mathrm {m} ^{2}}{\mathrm {s} ^{2}}}}$

Again, Nm 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 ohm versus ohm per square.