I'm using a torque wrench whose unit is cN.m. I wonder what unit this is, and how to convert N.m (Newton meter) to cN.m.

  • $\begingroup$ I've seen hPa (100 Pa) a number of times in datasheets as an alternate way to say 1mbar pressure, which is a common unit. (1bar = 10^5 Pa). $\endgroup$
    – Pete W
    May 20 at 12:27
  • 3
    $\begingroup$ @PeteW Over here in SI-land (continental Europe) hectopascals are the only unit ever used to express atmospheric pressure, so everyone is familiar with them from weather forecasts. $\endgroup$
    – TooTea
    May 20 at 14:57

100 cN.m are 1 N.m

The c before the N.m is pronounced centi. It's a standard SI prefix.

1 c of a unit is $\frac{1}{100}$ of a unit.

Therefore to convert toN.m you need to multiply cN.m with 0.01. $$0.01 \text{N.m} = 1 \text{cN.m} =1 \text{N.cm} $$

Probably the prefix centi is most commonly encounter used in centimeter cm.

Regarding the uses of cN.m or equally N.cm (which might be more convenient for some people), probably the most common usage (at least that I've personally noticed in recent times) in engineering would be as measuring units of the torque of stepper motors like NEMA 17. These motors are commonly used in 3d printers (e.g. have a look at this RepRap link) and other 'hobbyist' (or more professional) projects.

  • 1
    $\begingroup$ Only biologists and medics seem to use centimeters as a standard unit of length in the UK. Engineers invariably use meters or millimeters. $\endgroup$
    – alephzero
    May 20 at 9:49
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    $\begingroup$ @alephzero you are 100% right that mechanical/electircal engineers invariably use mm, however at least where I am from centimeter is a much more commonly used in a daily basis, eg height of a person. Also, - again at least where I am from - civil engineers tent to use in diagrams cm. $\endgroup$
    – NMech
    May 20 at 9:52
  • $\begingroup$ Are centinewtons actually units people that are lucky enough to not deal with the imperial system use? $\endgroup$
    – jko
    May 20 at 11:41
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    $\begingroup$ An easier way to think about it is Newton times centimeter. $\endgroup$
    – NMech
    May 20 at 12:33
  • $\begingroup$ Shouldn't this say "Therefore to convert in N.m you need to multiply cN.m by 100."? $\endgroup$
    – IMSoP
    May 20 at 20:17

cN.m = N.cm = 0.01 N.m

N.cm is more intuitive than cN.m.

'c' is a standard SI prefix indication one-hundredth as in centimeter, 0.01 m.


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