How to Create a Custom AutoCAD Paper Size from an Existing Size
For supported non-system plotters, the Custom Paper Size wizard can use an existing standard paper size as the starting point, then let you change media bounds and printable margins.
Start here — what you are going to do
Your goal: Create a custom paper size based on a known device media definition.
Where to start: Choose a known-good existing paper size close to the required custom sheet.
Beginner rule: The existing size is only a starting point; final dimensions and printable area must still match the real media.
Step by step — follow this in AutoCAD
Step 1 — Open the PC3
Where: PLOTTERMANAGER > double-click the non-system PC3.
Do this: Open Device and Document Settings.
Check: Correct plotter configuration is active.
Step 2 — Open Custom Paper Sizes
Where: User-Defined Paper Sizes & Calibration > Custom Paper Sizes > Add.
Do this: Start the wizard.
Check: Begin page appears.
Step 3 — Choose Use Existing
Where: Wizard > Begin.
Do this: Select Use Existing.
Check: Existing media list appears.
Step 4 — Select the base size
Where: Existing paper list.
Do this: Choose the closest valid media.
Check: A sensible base is selected.
Step 5 — Change dimensions
Where: Media Bounds.
Do this: Enter required width/length.
Check: Media matches project.
Step 6 — Set printable area
Where: Printable Area.
Do this: Adjust device margins.
Check: Border can print.
Step 7 — Name, save and test
Where: Paper Size Name / PMP / Finish.
Do this: Save and test the custom media.
Check: New size is usable.
Beginner example
A long plot uses the same 24-in roll width as an existing media definition but needs a 54-in cut length. Start from the existing roll definition and change only what is required.
Understand what AutoCAD is doing
Existing media can save setup work
It reuses known device settings.
It becomes a user-defined size
The original standard media remains separate.
Margins still need validation
A new length/source can change practical output.
Useful next guides: Add a Custom Paper Size to an AutoCAD PC3 · Edit a Custom Paper Size · Custom Paper Sizes: Complete Guide · Roll Paper: How to Set Custom Width and Length · PMP Files
Common problems and what to check first
| What you see | What may be causing it | Check this first |
|---|---|---|
| Wrong base size chosen | Source/orientation differs | Restart from a better base. |
| Custom duplicates standard | No need for custom media | Use standard size. |
| Test clips | Printable area wrong | Increase margins. |
| Other users cannot see it | PC3/PMP not shared | Deploy standards. |
When you need a more repeatable workflow
Document the approved base size and custom-media naming convention so users do not create many nearly identical definitions.
Official Autodesk references
AutoCAD labels and available media can vary by release, driver and output device. These Autodesk pages document the core workflow used in this guide.
Frequently asked questions
Does this overwrite the original size?
No.
Why use it instead of Start from Scratch?
It can be faster when the base definition is close.
Can system printers use this workflow?
System printers use manufacturer Custom Properties.
Explore more in CAD Paper Sizes, Margins & Printable Area.