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Confused about SI units

Message 1 of 6
593 Views, 5 Replies

Confused about SI units

 Hi, I am reasonably new to the 3D modelling side of AutoCAD and am a bit confused about the units of measurement.


I drew a simple Torus using the primitives toolbar and then the MASSPROP command to analyse it.


I got a calculated mass value of 88826439.6098 and a surface area value of 1776528.7922.


I was under the impression that any mass values would be displayed in kg and and area values in mm^2, yet these values seem rather large. Is mass presented as kg/m^3 or something?


I am probably asking a stupid question but have been working solidly for hours now and have got to the point where I cant think anymore.


Any information will be greatly appreciated!


Thanks in advance!

Message 2 of 6
in reply to: Anonymous



mass values and areas are depend on the units you start with for instance if you draw a rectangle:


- Dim 1x1               you will get area 1 sq.m

- Dim 10x10           you will get 100 sq.m

- Dim 100x100       you will get 10000 sq.m

- Dim 1000x1000   you will get 1000000 sq.m

Message 3 of 6
in reply to: Anonymous

I don't understand the question clearly ??
Did you get a rather large values than you expected ??
From engineering point of view the density is always presented in terms of kg/m3 , so if u drew in m and u wanted the results in mm you would have a rather large values .

If you would like, attach the drawing , and I'll try to help 🙂
Message 4 of 6
in reply to: imadHabash

Well I haven't needed to configure any of the units as I assumed they were already set to mm, though now I'm thinking that I am wrong and they were set to metres and somewhere along the line I have gotten confused.

Your answer somewhat answers my question but its more the mass units i'm not understanding.. I got a very large number, one that would make sense if the surface area were in m^2, but it was just a bit surprising how large the results I got were.


Just to confirm, AutoCAD - providing I havent changed any settings - will work and calculate measurements in metres and kg?


Thanks again.


Message 5 of 6
in reply to: NERDASORUS

I'm sorry, I was unbelievably tired and I couldn't quite word my question as I would have liked.


Yes, the values I got from using the MASSPROP command were larger than I had expected. I am thinking that if the entire drawing is drawn in metres then a mass value of 88*10^6 would be about right.


I am only doing a university assignment, so the drawings aren't particularly important at this point in time, but I need to write up a report at the end so I want to make sure that I am not getting confused with the values I assumed I was working in.


Thank you for your help.

Message 6 of 6
in reply to: Anonymous

The results are in the same units that you used to draw , if you used mm then the area is in mm and if in m the the area is in m
Again if u want to be more sure attach the drawing


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