Custom Paper & Roll collects practical CAD plotting guidance for this topic within Paper Sizes & Margins. Use these articles for setup, verification, troubleshooting and reliable final output.
Use a custom paper size only when the required physical media is not already available from the selected printer or PC3. The exact workflow depends on whether AutoCAD is using a Windows system printer or a supported non-system plotter configuration.
For supported non-system AutoCAD plotter configurations, custom paper sizes are added in the PC3’s Plotter Configuration Editor under User-Defined Paper Sizes & Calibration.
When AutoCAD uses a Windows system printer, custom-paper creation is handled through the printer driver’s Custom Properties rather than the non-system Custom Paper Size wizard.
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.
Edit a custom paper size when its dimensions, printable margins, name or source are wrong. Make the change in the same device/PC3 that owns the media definition, then retest the actual sheet.
Large-format plotters often use fixed roll widths with variable sheet lengths. Select the real plotter/PC3, create or choose a supported roll-fed media definition, and verify cutter/margin behavior with a test plot.