Explainer · what is a cui file autocad

What is a CUI file, and what does it control?

DWGDXFFree1,041 words

By Saumyajit Maity · Published 1 Feb 2022 · Updated 22 Sept 2025

A CUI file holds AutoCAD's user-interface customization. Almost everything you click — the ribbon tabs and panels, the pull-down menus, the toolbars, the right-click menus, keyboard shortcuts, and the workspaces that arrange them all — is defined in a customization file rather than hard-coded into the program. The CUI (and its modern CUIX form) is where those definitions live, which is how AutoCAD can be reshaped so thoroughly without touching its core code.

Most people never open one directly, yet they rely on it constantly. When your ribbon looks the way it does, when a custom command sits on a toolbar, when pressing a key fires a particular action — that is the customization file at work. It becomes something you actively manage when you tailor AutoCAD to your workflow, load a tool that adds its own menu, or need to recover after the interface gets into a mess.

Knowing what a CUI is, what it controls, and how to reset it turns a baffling 'my menus vanished' moment into a quick, calm fix.

What the CUI controls

The customization file is the master list of AutoCAD's interface elements and the commands behind them. It defines the ribbon's tabs, panels and buttons; the classic pull-down menus and toolbars; the shortcut (right-click) menus; double-click actions; keyboard and temporary-override shortcuts; and the workspaces that decide which of these are shown and where. It also stores the command macros that buttons run.

Because all of that is data rather than fixed code, you can add, remove and rearrange interface elements to suit how you work. Want a panel of your most-used commands, a custom button that runs a macro, or a shortcut that fires a frequent command? Those changes are recorded in the customization file, which is why backing it up preserves your whole tailored environment.

CUI versus CUIX

You will see two extensions, and the difference is mostly about packaging. The older .cui is an XML-based customization file. The newer .cuix is essentially the same customization data but stored as a compressed package that can also bundle the related resources — custom button images and similar — into one file. Modern AutoCAD works with CUIX as the main customization file format.

For practical purposes treat them as the same kind of thing: a customization file describing your interface. The chief advantage of CUIX is that it keeps a customization and its icons together in a single, portable file, which is tidier to share or back up. When older instructions mention CUI and your AutoCAD uses CUIX, the concepts map directly across.

Main, partial and enterprise files

AutoCAD does not rely on just one customization file. There is a main one (historically named acad, in CUIX form) that carries the standard interface. On top of that, AutoCAD can load partial customization files — smaller files that add their own ribbon panels, menus or toolbars without altering the main file. This is how a third-party tool can drop its commands into your interface cleanly.

There is also the concept of an enterprise customization file, typically a read-only shared file an office uses to push a common interface to everyone, while each user still keeps their personal customizations in the main file. This layering lets a company standardise the core interface centrally while individuals add their own tweaks locally, all coordinated through the customization files AutoCAD loads at startup.

Editing the interface with the CUI command

You rarely edit a customization file by hand. Instead you type CUI to open the Customize User Interface editor, a dialog that shows the customization files, their commands, ribbon, menus, toolbars and workspaces in a tree you can drag and drop. From there you create commands, write their macros, place them on panels, build or modify workspaces, and load or unload partial files.

This is also where you load a partial CUIX that came with a tool, set the current workspace, or assign keyboard shortcuts. Because everything is editable through this one dialog, customising AutoCAD is a matter of arranging elements visually rather than coding. The changes you make are saved back into the relevant customization file, taking effect immediately in the interface.

Resetting a broken interface

Customization is powerful, which means it can also go wrong: a botched edit, a misbehaving partial file, or a corrupted customization file can leave the ribbon empty, menus missing or buttons firing the wrong command. The reassuring part is that this is recoverable, because the interface is just data in a file.

The blunt fix is to reset AutoCAD's interface to its shipped defaults, which restores the original main customization file — useful when you cannot tell what broke. A gentler approach is to unload a suspect partial file in the CUI editor and see if the problem clears. Either way, keeping a backup copy of your customised CUIX means you can restore your tailored setup after a reset rather than rebuilding it. Treat the customization file like any other important configuration: back it up, and you can always get your interface back.

Free download

Browse the full library — DWG & DXF, no signup.

Download CAD blocks

Questions

Frequently asked

What does a CUI file control in AutoCAD?+

It defines the user interface — ribbon tabs and panels, pull-down menus, toolbars, right-click menus, keyboard shortcuts and workspaces — along with the command macros buttons run. Because this is stored as data, the whole interface can be customised without changing AutoCAD's core code.

What is the difference between CUI and CUIX?+

Both store interface customization. The older .cui is an XML file; the newer .cuix is a compressed package that also bundles related resources like custom button images into one file. Modern AutoCAD uses CUIX, but the concepts are the same.

How do I reset my AutoCAD interface to default?+

Reset the interface to its shipped defaults, which restores the original main customization file — handy when the ribbon or menus break and you cannot tell why. Back up your customised CUIX first so you can reload your personal setup afterwards.

How do I edit the ribbon or add a custom command?+

Type CUI to open the Customize User Interface editor, then drag and drop to create commands, write their macros, place buttons on ribbon panels and build workspaces. Changes save into the customization file and appear in the interface immediately.

Related downloads