The office sends you a .ctb file and tells you to put it on your machine. You do, you open the plot dialog to pick it, and the name is nowhere in the list. That is where plot styles in AutoCAD usually go wrong: the file exists, but it is either in the wrong place or the drawing cannot read that kind of file at all.
This article measures every step on AutoCAD 2027 at the Institute. For a proper grounding in linework and plotting see our AutoCAD for Construction course.
What a plot style table actually changes on paper
Rather than assert it, we measured it. We built one drawing of five lines in five colours. Their lineweights were set to 0.09, 0.18, 0.35, 0.53 and 1.06 mm. That drawing was then plotted to PDF three times with three different plot style tables, and every stroke was read back out of the PDF files.
Three results, three lessons.
With acad.ctb, every colour prints as itself. Colour 7, the one that shows white against the dark screen, comes out black on paper. That is why a drawing that looks white still plots legibly.
With monochrome.ctb, all five strokes come out black. With Screening 50%.ctb, the colours survive but at half the ink.
And the part worth remembering: none of the three changed the width of anything. All three PDFs measured 0.08, 0.17, 0.34, 0.55 and 1.06 mm, matching the lineweights set in the drawing. Those three tables only touch colour and ink density.
That is not to say a plot style table cannot touch width. Autodesk's About Plot Style Tables page for the 2027 release is explicit: "Color-dependent plot style tables (CTB) use an object's color to determine characteristics such as lineweight". It can override width. The three tables shipped with the program simply choose not to. An office file usually does, one width per colour.
Adding a ctb file: it is accepted from one folder only
This is where most attempts fail. We copied the same .ctb file into three different places and tried assigning each to a drawing.
| Where the file was put | What the program answered |
|---|---|
| The AutoCAD Plot Styles folder | accepted |
| An ordinary folder on drive C | refused |
| Right beside the open drawing file | refused |
| A name with no file behind it | refused, reporting Automation Error. Invalid input |
The one folder that works, read straight out of the program's own settings:
C:\Users\<your name>\AppData\Roaming\Autodesk\AutoCAD 2027\R26.0\enu\plotters\Plot StylesThat path changes with the user name and with the release, so copying it verbatim onto another machine is usually wrong. The same Autodesk page notes: "Both color-dependent and named plot style tables are stored in the Plot Styles folder by default".
One measured point contradicts a lot of advice in circulation: no restart is needed. A file copied into that folder was accepted immediately, in the session already running.
Finding the plot styles folder without typing a path
You do not have to hunt for the folder. The routes below are read straight out of the acad.cuix interface file of the 2027 release on the machine.
| Command | Alias | Ribbon | Classic menu |
|---|---|---|---|
STYLESMANAGER | none | none | File → Plot Style Manager |
PAGESETUP | none | Output → Plot → Page Setup Manager | File → Page Setup Manager |
PLOT | PRINT, DWFOUT | Output → Plot → Plot | File → Plot |
Type STYLESMANAGER and press Enter, and AutoCAD opens the Plot Styles folder for you. Paste the file there and the copying half is done. This beats typing a path, because the program already knows the folder belonging to the release you are running.
Worth noting: STYLESMANAGER has no ribbon button at all, and no alias. Anyone who works only by clicking will never find it.
Telling the drawing to use it, step by step
Copying the file in is only half the job. The drawing still has to be told to use it.
| Step | What you do |
|---|---|
| 1 | Type PAGESETUP, pick the layout, click Modify |
| 2 | In Plot style table, choose the .ctb file you just copied in |
| 3 | Tick Plot with plot styles under Plot options |
| 4 | Tick Plot object lineweights if the widths are to have any effect |
| 5 | Click OK, then Close, and the layout remembers it |
Step 3 is the one people skip. Choose the file but leave the box unticked and the drawing still plots in its original colours, which looks exactly like a broken file. Most complaints about plot styles in AutoCAD not working end at this one tick box.
Do this in PAGESETUP rather than in the PLOT dialog each time. Set once in the page setup, the layout keeps it. Organising layouts and viewports is covered in our article on layouts in AutoCAD.
The list is empty: colour-dependent plot style tables and named ones
This is the hard case, and it has nothing to do with where the file sits. Your drawing is in named mode rather than colour mode.
AutoCAD has two kinds of plot style table. The colour kind uses the .ctb extension, the named kind uses .stb. A drawing follows exactly one of them, and the PSTYLEMODE variable says which.
We measured both directions:
| Drawing | Assigning a .ctb | Assigning an .stb |
|---|---|---|
PSTYLEMODE = 1 (by colour) | accepted | refused |
PSTYLEMODE = 0 (by name) | refused | accepted |
Blunt and consistent: a drawing in named mode cannot read any .ctb file, not even the acad.ctb that ships with the program. That is why the list is empty, not because the paste went to the wrong folder.
To check which mode you are in, type PSTYLEMODE and press Enter. A second variable, PSTYLEPOLICY, decides what new drawings get: set it to 1 and new drawings come out in colour mode, set it to 0 and they come out in named mode. We created a drawing with each value and confirmed it.
Converting a drawing between the two modes
CONVERTPSTYLES does this, and the two directions behave very differently.
Named to colour is easy. Run it on a drawing with PSTYLEMODE = 0 and the program asks nothing at all, reporting a single line:
Drawing converted from Named plot style mode to Color Dependent mode.
Measured immediately afterwards: PSTYLEMODE moved from 0 to 1, and .ctb files were accepted from then on.
The other direction has a trap. Run it on a drawing already in colour mode and it asks:
Enter a Named plot style table to assign:
We answered acad.stb, a file that ships with the program, and were refused outright:
Acad.stb does not contain a color mapping table and
cannot be used to convert drawings. Select a different
named plot style table.So not every .stb can be used for the conversion. It has to carry a colour mapping table, and that is what CONVERTCTB produces when it turns a .ctb into an .stb. The correct order is therefore CONVERTCTB first, then CONVERTPSTYLES.
In practice the first direction is the one you need: a consultant's drawing arrives in named mode and has to be brought back to colour mode to match the office set of .ctb files.
Lineweight display, and why the screen never changes
You set lineweights on every layer, look at the screen, see no difference, and conclude nothing happened. The image at the top of this article is exactly that: the two panels are the same drawing, the same five lines, with nothing edited between them.
The difference is the LWDISPLAY variable. Measured on the machine, it defaults to 0, meaning off. Set it to 1 and the screen shows the widths at once.
Remember that LWDISPLAY only changes what you see. It does nothing to the printed sheet. A 1.06 mm line plots at 1.06 mm whether you have it on or off, exactly as the measured table above shows.
Two companion variables are worth knowing. LWDEFAULT is the default width for a layer, measured here as 25, meaning 0.25 mm. LWUNITS at 1 means the units are millimetres. Assigning widths per layer is covered in our article on layers in AutoCAD.
Nine plot style tables already on your machine
Before going looking for a file, see what Autodesk already installed. Counted in the Plot Styles folder of the 2027 release on the machine: 9 .ctb files and 4 .stb files.
| File | What it does |
|---|---|
acad.ctb | keeps each object's own colour and width |
monochrome.ctb | forces every colour to black, widths untouched |
Grayscale.ctb | plots on a grey scale |
Screening 25%, 50%, 75%, 100% | progressively lighter ink |
Fill Patterns.ctb | changes how hatched areas are filled |
DWF Virtual Pens.ctb | for virtual DWF output |
The four .stb files are acad.stb, monochrome.stb, Autodesk-Color.stb and Autodesk-MONO.stb.
For most coursework and internal drawings, monochrome.ctb is enough. It gives a clean black and white sheet while preserving the thick-to-thin hierarchy you set up on the layers.
Four things people say that are not true
| What people say | What the 2027 release actually does |
|---|---|
| You must restart AutoCAD after copying the file in | You do not. A file copied into the Plot Styles folder was accepted in the running session |
A .ctb next to the drawing works too | It is refused. We tried twice and were refused both times |
| An empty list means you pasted into the wrong folder | There is a commoner cause: the drawing is in named mode, PSTYLEMODE of 0 |
| The plot style table decides line width | None of the three shipped tables touches width. Width comes from the lineweight set in the drawing |
Whether you call it adding, loading or installing, plot styles in AutoCAD come down to two movements: put the file in the right folder, then choose it in the page setup.
Frequently asked questions
Where does the .ctb file go?
Into the Plot Styles folder of the release you are running. The safest route is STYLESMANAGER, which opens that exact folder for you to paste into.
Do I have to restart AutoCAD afterwards?
No. We copied a new file in and assigned it to the open drawing straight away, and it was accepted.
Why is the plot style list empty even though I pasted the file?
Most likely the drawing is in named mode. Type PSTYLEMODE to check. If it reports 0, run CONVERTPSTYLES to bring it back to colour mode.
I set lineweights but the screen looks the same.
Set LWDISPLAY to 1. It defaults to 0, so the screen draws every line thin even though the sheet plots correctly.
Everything prints in colour and I want black and white.
Choose monochrome.ctb in the plot style table box, and remember to tick Plot with plot styles. The file is already on your machine.
Can I edit the office .ctb file?
Yes. Double-click it in the Plot Styles folder to open the editor. In a colour table, though, you can only change the colours that are already there — as Autodesk puts it, "you cannot add or delete plot styles".