Understanding scale concept and units in Autocad…
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Author | Orhan Toker |
| Profession | Architect M.Sc. | |
| Autodesk Authorized Consultant | ||
| Database Specialist | ||
All Autocad versions
Hello,
I wanted to write this article, which will help you to understand the AutoCAD’s working logic and learn some concepts like scale and unit, if you have just started using AutoCAD or if you are learning it by yourself.
First of all, I would like make clear that, whichever drawing you are making, area that you are substantiating this drawing is called modelspace. If you are using AutoCAD 2000 or higher versions, you have noticed phrases like “Model / Layout1 /Layout2” over the small tabs under the area which you are making the drawing. Do not forget that you make your drawing in Modelspace.
Just on the lower left corner of Modelspace, there is an icon that shows x and y axes. This is called UCS (User Coordinate System) icon. This icon shows the coordination system according to which you are currently making your drawing. Arrows pointing at x and y directions shows the + direction of Modelspace.
Now we can mention the subject of scale and unit. Coordinate system in AutoCAD Modelspace is cartesian coordinate system. If you take 0,0 point as origin where x and y values are 0 (this is the lower left corner of your screen), values towards right and up will be positive. Accepting 0,0 point as origin, x-axis is 0 degree towards rigth according to degree angle system. Angles will be according to counter clockwise, y-axis will be 90 degrees in + direction, x-axis will be 180 degrees in – direction, and y-axis will be 270 degrees in – direction.
We know that the drawing you make in AutoCAD is called model and the area in which this drawing is made is called Modelspace. This point is very important, drawing isn’t done by scale like it is done on paper, it is done as 1=1 and scaling is made when printing on paper. However, it is important how you accept 1 AutoCAD drawing unit. AutoCAD paper (layout) unit is mm(milimeters). Let’s say, you are drawing a architectural project and you accept 1 drawing unit as 1cm. So, you started your drawing with the assumption of 1 dwgUnit = 1cm. You continue drawing according to certain rules like the doors will be 100 units, height of tables will be 75 units. Thus, you draw everything on the cm basis. When you take print out, if you don’t change the scale, each 1cm will look 1mm as the AutoCAD unit is milimeters(mm). In other words, it will be printed as 1 dwgunit (we accepted as cm) = 1mm, which means 1/10 scale. In order to take print out, you should state in the scale part that your 10 drawing unit (that is to say 100 mm) shall look 1mm on paper, which is 10=1.
I hope it does not look complicated. In order for your AutoCAD drawings to be precise and to take print outs according to any scale at any time you desire you should make an acceptance for 1 drawing unit and you should draw according to one on one scale.
I will be glad to answer if you have questions. I wish you nice works.
Read in other languages: TR
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January 3rd, 2007 00:52
Hi, I just found your blog and I can see I will visit it often! Very nice tips and your style is easy to understand!
February 21st, 2007 15:15
Nice, simple, straightforward Thanks
February 27th, 2007 22:58
thanks,understanding scale&units,i will visit your lessons all time
March 2nd, 2007 07:32
Good day thank you very much for your clear explanation and tips. Can you give us tips for a multiple scale in one drawing sheets
March 2nd, 2007 09:29
Hello Ricardo,
You can create more than one MVIEW for each layout. And in MODEL SPACE mode you can zoom each viewport seperately.
March 5th, 2007 18:28
Hi,
I have a question. I have been using ACAD professionally ever since release 9. I have seen Model space and Paper space develop over the years, and I appreciate the way they make scaling to actual paper (plotting) easier. Esp. when producing architectual or civil drawings, drawing in model space where every drawing unit represents 1mm is great and then just scale them to paper space when plotting is neede. However, I have never found a solid and good solution when it comes to text. Drawings must conform to standards (ISO for example) and when I draw something in modelspace and need some text with it, I must calculate the textheight accoding to the scale I will be plotting in. Ok, at first glance not a big problem. text that needs to be 2.5 mm high on the plot I just draw 250 when the scale is 1:100, but what if I want to plot in 1:100 AND 1:50 ?? The text-height comes out all wrong. Placing text in paperspace is not an option either because sometimes different scales mean different paper-sizes (A0 becomes A1 etc.) which means that all text is in the wrong place.
So, do I overlook something or is there no “simple” solution?
March 6th, 2007 08:50
Hi Bert,
Please try SPACETRANS, SCALETEXT and JUSTIFYTEXT commands. These three commands esp. designed for MSPACE/PSAPACE transitions.
I hope this makes easier to scale your texts
March 6th, 2007 11:36
Hi Orhan,
Thnx for the reply, but I really don’t see how this makes things easier. Spacetrans only works in paperspace, and when there is a drawing with 10 or more layout’s attached to it all with different scales this means I have to apply the same text 10 times or more. Besides, like I said, placing text in paperspace is not very efficient because when something changes in modelspace (or if the viewport changes) I must accomodate for that in every paper space.
Scaletext and justifytext would seem a better option, but again, if I need to plot something I must change the textheight for every plot. This can be a tedious job and easilly forgotten.
Plus, what about attributes that are often part of blocks. They alway’s reside in modelspace.
If I could add my 2 cents to a wishlist I would opt for text having a relative scale attribute that automatically adjust when plotting.
March 6th, 2007 22:27
Sorry Bert,
All i know about text scale was that. Hope visitors can answer your issue.
See you again
March 12th, 2007 13:31
I would like to know how I can make wall which has two lines goes parallel to each other and when I need to make a door how can it close and after space of a door how can it continue to make another room
March 20th, 2007 11:58
I am tranee AutoCAD before that i have some problem in printing and adjusting scall in printing but after reading your good topics about that all the my problem solve and I appriciate your efforts
March 27th, 2007 08:11
[...] about scaling or aligning the drawing in the middle of the paper. You can read my article “Understanding scale concept and units in Autocad“ where I have explained these concepts in detail.When you first start drawing in model space [...]
April 13th, 2007 09:40
Hi,totally good tips for beginner..You had done a great and kindness job ever. Thousand of thanks are not enough for that. I would enjoy see more tips from you! Thanks again.
April 16th, 2007 06:32
hi
now its very clear to me about scale concept.thanx.i have some problem about osnap command.please clear it for me .i am a civil engineering diploma student.
April 16th, 2007 15:21
to avoid text scaling when printing drawings I usually place all text in paperspace regardless of how many viewports on many different scales are used in the drawing, by doing this you guarantee that all text are of the same size, you do not have to make additional setup for different viewports, if you place text in model space you inevitably have to make calculations to make it all look of the same size when you go to paperspace
April 18th, 2007 09:58
Hi,I am new to auto cad.
If the drawing scale is 1:250 mentioned in title box (all dimensions in mm) and i have to draw circle of 79 meters radius.Now pls let me know that i have give draw circle of 316 radius so that it can show 79meters.
Pls clear my dought
April 18th, 2007 13:38
Hi Pankaj,
Like i mentioned in my article, if you want to draw a circle with 79m radius you should enter 79000 as radius. Of course with accepting your 1dwg unit = 1mm
April 19th, 2007 07:58
[...] Related Articles: Understanding scale concept and units in Autocad [...]
April 19th, 2007 13:05
can you help me how to use autocad?what the work environment and tool(basic command)thnk you sir
April 20th, 2007 11:17
thanks for the explanation!
I was wondering: if i draw in cm in model space (1 unit=1cm) is there a way to set up the layout units in cm also and not mm … I use a field (in layout) with a custom scale attribute and it shows 1:10 scale while I’m printing a 1:100 scale on paper….is there a way to change this so that 1:100 on screen is 1:100 on paper. Thanks
April 24th, 2007 09:47
I have a 3D model of a process plant that I need to annotate and dimension in paperspace, I need to have hidden lines removed when I plot the drawing which I understand I have to do in the viewport properties not in the plotting dialogue box. However !!!! My tanks and pumps have no center lines in the model so I add them manually in the paperspace when I dimension from a paperspace object to a modelspace object (as I did in Autocad 2000) if my dimlfac variable is not set to the correct value I don’t get the correct dimension. I think Autocad cad now picks up the scale of your viewport and sets the dimlfac accordingly is their a variable I can set to ignor the viewport scale so that I can set my dimlfac once and then dimension to scale regardless of whether the object I am picking is in modelspace or paperspace ?
April 25th, 2007 08:09
[...] As I follow the forums and questions, most of you have difficulty in plotting. Even though there are several articles that were written about the subject, I can clearly see that you don’t read them carefully . In order for you to understand this article better I suggest you to read my previous article “Understanding scale concept and units in Autocad”. [...]
April 25th, 2007 08:46
D/Sir,
Would you like to suggest good books for beginners
on autocad (mehanical).
Thanks & Regards.
April 27th, 2007 07:44
Hi Kksingh,
Sorry, I’m not fallowing the published books on AutoCAD worldwide. May be our readers suggest their favorite books.
April 30th, 2007 08:11
[...] scale. By this way, we will get rid of problems of scaling a little bit, as mentioned in articles Understanding scale concept and units in Autocad and Scaling in Autocad drawings and [...]
May 1st, 2007 09:59
[...] Articles: Annotation Objects in AutoCAD 2008 - 1, Understanding scale concept and units in Autocad, Scaling in Autocad drawings and layouts, Advanced plotting using [...]
May 16th, 2007 15:25
I’m new to autocad. I drew some plans and saved the dwg. when I move the dwg to another autocad version. the scale isn’t what it should be. where my stud should be 6″ actual it ends up being something like 108. But this only happens when I load my other dwg. If I make a new one everything is what it should be. I’m sure there is some unit/scale I misunderstood when I first drew the dwg… any suggestions on how to rescale, so I don’t have to re draw it? thank you!
May 24th, 2007 17:26
Sir
I am just starting to learn autocad by self. I am reading a lots of tips from net. I started with the origin point. When I put 0,0 or any other number in this format it is not giving me a straight line. it is slanting backwards and making a half triangle
Please advise me
Cherian
May 25th, 2007 08:40
Hi Cherian,
Please read my “Coordinates in AutoCAD” article.
Have a nice weekend
May 25th, 2007 10:31
i’m self-studying and practicing autocad and i tumbled into your blogs in one of my searches…i’m relieved. im sure i will visit it often coz i can see that your style is very simple and easy to understand. in fact, today i’ve learned a lot!
June 6th, 2007 18:19
is the mesaurement o scale is different for modelspace and layout space i relly very confuse about these scale and i also like to know about precision???????
thanx in advance for help
June 14th, 2007 18:50
I have only started working with autocad in the last 4 weeks and I find your tips great.At present I`m having trouble getting my head around the units and scaling with regards my work. The basis of this is drawing, scanning OS maps as bases for adding site information to. I can draw objects at 1:1 and get it but I`m having a mental block applying it to maps which are already scale drawings….Help.
June 27th, 2007 05:04
yeah sounds easy…
don’t you think so,
cool
July 3rd, 2007 06:30
I have been reading several atrticles to get an idea of this scaling buisness in Autocad, Finally I found the right place, Thanks for your explanations. it is simple & easy to understand.
Further I would like to know how draw one object in different scales. for an example I want to draw a cross section of a road in two different scales in X-direction & Y-direction 1:50 & 1:20 respectively. Do I still draw this in 1:1 scale in model space & do the adjustment when the prints are taken. please explain… also explain about viewports & layouts and models
July 3rd, 2007 08:32
Thank you kinigama,
Please read http://www.dailyautocad.com/autocad/advanced-plotting-using-layouts/ article. And chackout our http://www.dailyautocad.com/category/printout/ category.
October 11th, 2007 09:00
[...] Understanding scale concept and units in Autocad [...]
October 21st, 2007 04:36
hey! what a great resource.
I have searched your data and can’t figure out the answer to my question. If anyone can help… I’d be very happy.
Here’s the scenario: I started using AutoCAD at work this year. Picked up the basics pretty well. Now I have it at home and can’t figure out how to change my modelspace. At work, we can draw anything no matter how big. At home, I can’t figure out how to make the modelspace larger. I draw a line 12″ long (just for testing) and zoom out but the line is still VERY visible. I need to plan a room in a home but when I enter the dimensions in inches the plan is too big to view (can’t zoom out far enough). How can I set the space to accommodate any drawing?
Thanks
October 22nd, 2007 14:17
A great many people think they are thinking when they are merely rearranging their prejudices — William James
October 25th, 2007 05:20
I looked around the net and asked a few friends for a few hours now, but still i cant find a solution to my problem.
Ive have drawn in model space so that 1 dwg unit = 1 metre, and i’m now trying to set up my layout to a standard scale. However after much confusion I have realised that my paper space units are in inches for some strange reason, ie when i draw a line in paper space it measures in inches.
I checked Format => Units and sure enough it was in inches, so i changed it to millimetres, however it still draws in inches. I then check the page setup to make sure everything was in metric units, but still the problem persists.
Can anyone suggest what is going on and how to resolve this?
Thanks,
Rick
October 25th, 2007 08:16
Hello Rick,
I think problem is your plotting device settings. Please try to select DIN format papers (e.g. A4 A3 ..). If this can not solve focus on your Windows control panel. look at your locale settings are metric or not.
October 26th, 2007 06:08
thanks orhan,
turns out my title block that i was importing into the drawing was in imperial, and overiding the overall metric units of the drawing. Thanks again for the help.
November 3rd, 2007 19:10
Can I have an information on “Attribute” related to Block?
November 6th, 2007 09:03
I had taken Autocad classes a while ago using Autocad 2000/2002 versions, and now I’m about to use Autocad again after 5 years of break. As I’m trying to brush up my CAD skills quickly, can anyone tell me what’s been changed between version 2002 and the current version, 2008 (?).
Thanks for your help,
November 9th, 2007 15:26
what is the use of grid setting and snap when i print to scale 10:1
November 22nd, 2007 12:33
hi,
I am a beginner and my knowledge on acad is limited. i hope you would help me solve this problem. I have created many drawings of mechanical components in A4 sheet format and to the true size. some are very big, say 2000mm by 1000mm and some are small say about 100mm by 60mm. now my boss wants everything in an A0 sheet. As you know naturally the smaller components get shrunk when i bring all dwgs in A0. so I tried to resize/scale the smaller components but the dimension also gets changed. Do i have to override all dimensions to scale the particular component dwg so the dimensions are not affected? Or is there a way to scale the object/component drawing with out updating/affecting the original dimensions? i hope i have put it rightly. Thanks in advance.
senthil
November 23rd, 2007 09:47
Hi Senthil,
I Think your old parts drawn with scaled dimensions. E.g. 1000mm length is reduced 100mm as in 1:100 scale drawing. If so you have to dimension them again after scaling 1/1.
Please explain what is your sitiuation.
November 24th, 2007 10:01
hi there…im having a problem in making roof gutters in my 2008 version..can you help me..please email me right away..thanks!
December 7th, 2007 07:01
Hi,
My knowdege about AutoCAD is very limited. And things about Model/Paper space, units and scales trouble me most. In your article,
You said it is important how users accept 1 AutoCAD drawing unit.
So exactly how? Say I want to let 1 drawing unit = 1 feet or 1 cm? What are the commands I should go through?
December 7th, 2007 07:06
Hi,
Forget to ask one more question:
What is defined as a drawing unit?
December 7th, 2007 09:46
Hi Tedina,
First of all, work in model space and use layouts as paper.
In modelspace, when you enter “1″ for any distance inputs, Autocad draws 1 DWG unit. here is mini table for 1 DWG unit
In architectural discipline
ANSI std: 1DWGunit can be accepted as 1 ft or 1 inch
DIN std: 1DWGunit can be accepted as 1cm or 1m
In mechanical discipline
ANSI std: 1DWG unit can be accepted as 1 inch
DIN std: 1DWG unit can be accepted as 1 mm
December 7th, 2007 17:37
Hi, Orhan
Thanks for your quick reply.
But, you said 1 DWGunit “can be” accepted as 1 ft or 1 inch. Are u saying there is no way to tell AutoCAD what 1 drawing unit really represent?
Maybe I wasn’t clear in the previous comments/questions. What I am asking is how to tell AutoCAD to make 1 drawing unit equal to 1 cm or foot in real world regardless of what disipline I am in?
Thanks
January 2nd, 2008 20:20
Great blog. I have a question regarding “Primary” and “Alternate” unit dimension location. Standard options in 2004 dimensioning allows the “Alternate” dimension to be placed eith below or beside the primary dimension. Our customers are asking if we can show the “alternate” units (mm) above the primary units.
I’ve seen several other software programs that allow various placements of alternate dimension but can’t seem to find it in Autocad.
Is this an option on the latest versions?
Thanks
January 7th, 2008 22:27
Dear, Orhan Toker
I have a long term goal, its my dream to alway design my own house, i know it will defently take time, but i have taken the first step to learn and get more knowledge on arhitecture. I want to know whats the best program to use to design my own house, and how can i go about on doing this goal that i have. What are the main things i need to be looking at. I was considering Autocad and learning out of the lessons you have so i know what to expect, they are very good, i just want to make sure i’m heading the right direction.
Thanks,
January 8th, 2008 09:57
Hi Rebecca,
I prefer REVIT building for architectural drawings. But Home3D is cheaper
of course
March 10th, 2008 08:07
i can’t undrstand properly
can i do work within model space through mvsetup?
March 10th, 2008 10:11
Yes you can work in model view window on layout tabs, or model tab directly.
March 12th, 2008 04:48
hello, i just read yuor blog and gain knowledge but can i ask something im concerned? for example i have a drawing in the cad and if printed i want it to be scale so my foreman will understand the distance using his steel tape without hassle for me to put dimension. like i want it to print in 8.5×13″ white paper and hope after printing its already scaled example 1:50. what will u advise?
April 9th, 2008 12:46
dear experts
how can i display the co-ordinate points in the working plane.
April 9th, 2008 18:42
U can use ID command to get coordinate info of any point. Buy unfortunataly an autolisp or other macro reqired to print their coordinates on screen.
Regards
April 24th, 2008 19:55
I am having troubles exporting a PDF to AutoCAD and having the scale be correct. Once the pdf is exported as a .dgw into AutoCAD, how do I scale it to full size so the measurements are correct? My measurements are off quite a bit because when I look at the measurements of the room on the pdf they are quite a bit larger than the measurements once it is converted to AutoCAD.
Thank you!
May 5th, 2008 23:21
Nice article, really helpful. Cheers.
May 10th, 2008 16:28
Hi
This point is very important, AutoCAD is Scale less software!
In AutoCAD we have two different Drawing Scale:
1-Draw scale =CAD drawing and real world measurement. (for example 1/100)
2-Plot scale factor =CAD drawing and plot sheet size (for example 1/1)
Note: If you know the sheet size that you’re going to use and real-world size of the building plan you’re going to draw, and you want to find out the largest drawing scale factor you can use:
1.Divide the X dimension of the building by the X dimension of the sheet.
2.Divide the Y dimension of the building by the Y dimension of the sheet.
3.Take the larger number from the calculations in steps 1 and 2.
4.Round up to the nearest “real” drawing scale factor that’s used in architectural drafting
June 13th, 2008 01:40
I just found Daily AutoCad.
I am newly employeed at a consulting engineering firm.
I know nothing about autocad. I have opened it & played around, but still can’t draw anything.
Can you suggest where I should begin for learning on my own? Is there step by step information somwhere?
Please let me know where to start.
Thanks very much,
Sidney
June 26th, 2008 12:47
i have a drawing i need to calculte lenghts
scale is 1:750
sheet is A0
so kindly advice me 1 unit of drawing is equals to how many of actual
June 27th, 2008 10:25
@Salman,
In paper space,
1 DWG Unit = 750 paper unit (mm acceptance)
1 DWG Unit = 75 paper unit (cm acceptance)
1 DWG Unit = 7.5 paper Unit (m acceptance)
Bye
July 3rd, 2008 09:01
Hi it is simple
i want ot know more about lline standared thikness in drawing will giving print
Viral Panchal
Suzlon Energy ltd India
July 31st, 2008 11:53
hi.
i m new user of auto cad, i am facing some problem in making a dimenson style like m,cm,mm
sir will you send me some tips about these three dimensiom style,
thanks
August 16th, 2008 10:54
Hello Sir, I just found your blog and I can see that you teach very clear I will visit your site regularly ! Very nice tips and your style is easy to understand!
It is very helpful for us student taking up architectural Engineering….
nice job and keep it up your good work
God Bless You….
August 17th, 2008 10:46
Yo’re well come julius.
I’m glad to see your good words.
Regrads
August 27th, 2008 21:07
I have a dilemma, I usually only work with architectural scales and now I have a project they want in metric. They plan to build a model of a room so I used the 1:50 scale. I have to explain in simple terms on how they are to build it. What does the 1 mean and what does the 50 mean. I can see if it was 1cm=50m but I don’t know how to explain it to the customer on how to build and read this. Can you help me expain?