AutoCAD Lineweights & Plot Thickness Guide

Lineweights are the printed thicknesses that make some lines look stronger than others. They can come from layers, individual objects or plot styles, so fixing a lineweight problem starts by finding which of those places is actually controlling the final output.

Start here — what you are going to do

Your goal: Find why a line prints too thick, too thin or the same thickness as everything else.

Where to go: Check Layer Properties/Properties first, then Layout > Page Setup > CTB/STB and Plot Options.

Beginner rule: Change one thing at a time. After each important change, use Preview or create one test PDF/print before continuing.

Step by step — follow this in order

Step 1 — Pick one line that prints incorrectly

Where: In Model/Layout, click the problem object.

Do this: Use one test object so you can trace its settings from drawing to output.

Check: You should know its layer and object properties.

Step 2 — Check the layer lineweight

Where: Home > Layers > Layer Properties Manager.

Do this: Find the object layer and read its Lineweight value.

Check: Note whether the layer sets a real lineweight or Default/ByLayer.

Step 3 — Check for an object override

Where: Select the object > Properties palette.

Do this: Look at Lineweight and confirm whether it is ByLayer or explicitly overridden.

Check: If an override exists, decide whether it is intentional.

Step 4 — Check CTB/STB

Where: Layout > Output > Page Setup Manager > Modify > Plot Style Table.

Do this: See whether the plot style overrides lineweight for that color/style.

Check: You now know whether the style table changes the layer/object value.

Step 5 — Check Plot Options

Where: Page Setup > Plot Options.

Do this: Make sure plotting object lineweights/styles is enabled as required.

Check: Preview should show the intended hierarchy.

Step 6 — Print a lineweight ladder

Where: Create/plot several known lineweights.

Do this: Compare PDF and physical plot, because the device can affect the visual result.

Check: Approve a range that is readable on the actual output device.

A simple example

One layer prints too heavy

If one layer looks too thick on paper, check whether the layer has an explicit lineweight, whether its objects override that value, and whether the CTB/STB applies another lineweight. Change the setting that actually controls the output instead of guessing.

Where lineweight can come from

Start with ByLayer

A maintainable standard normally assigns most object lineweights ByLayer, with exceptions documented.

Object overrides

Per-object lineweight can intentionally override the layer but is easy to lose in large projects.

Plot style override

CTB/STB can override or transform plotted weight depending on the standard.

Screen vs printed thickness

On-screen lineweight display is not a calibrated preview of ink on paper.

Output device limits

Very thin weights, screening and dense hatches can repeat differently by output device.

How lineweights are resolved at plot time

Hierarchy over exact numbers

The purpose of lineweights is visual hierarchy: cut/profile, primary object, secondary object, annotation, hatch/background. Exact millimetre values vary by discipline and device; the hierarchy must survive reduction and reproduction.

Half-size plots

A full-size lineweight standard may become visually dense on half-size output. Decide whether the office intentionally scales lineweights or uses a separate half-size plot style; do not let users improvise per sheet.

Screening

Screened lines can communicate existing conditions or secondary context but may become too faint on office lasers or after scanning. Test the complete document lifecycle.

Calibration record

Keep a dated PDF and physical calibration sheet for each production device. When users report “lineweights changed,” compare against the record before editing the CTB.

Common problems and what to check first

What you see	What may be causing it	Check this first
All lines same	Plot object lineweights off or style maps identical.	Trace one object through all property sources.
Lines too thick	Object/layer plus CTB override or scale lineweights option.	Compare property and plot style values.
Lines disappear	Weight/screening too light for output device.	Plot calibration ladder.
PDF looks heavy on screen	Viewer thin-line rendering/zoom.	Inspect at 100% and physical sample.
One layer inconsistent	Object overrides.	Use property audit/select similar to find exceptions.

For a consistent lineweight hierarchy

Create a lineweight ladder that shows the office’s thin, medium and heavy values. Print it through the actual CTB/STB and the real PDF/plotter path. This gives users a visual standard instead of relying only on numbers in a settings dialog.

Official references

Autodesk — Plot styles and lineweight-related output

Frequently asked questions

Why do lineweights look different on screen and paper?

CAD display uses a screen approximation, while plotted output uses physical lineweight values and device rendering. Zoom level can also change how PDF linework appears.

Can a CTB override layer lineweights?

Yes. Depending on its settings, a CTB can assign plotted lineweights based on indexed colors.

Why are all my printed lines the same thickness?

Possible causes include plot-style mappings, object/layer settings, disabled lineweight plotting or output-device rendering. Check the Page Setup and plot style before changing the drawing standard.

What is the best way to choose office lineweights?

Plot a representative lineweight ladder on the actual target PDF and physical devices, then select a hierarchy that remains distinguishable at full-size and any required reduced-size output.

Explore more in Plot Styles & Lineweights Guide.

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