What's New in AutoCAD 2021?

  • Updated

By Miles Nicholson


The following is a summary of the primary improvements to the AutoCAD 2021 release.

AutoCAD 2021 provides a set of enhancements based on customer feedback, surveys and analytic data that prioritise Autodesk’s efforts. Several features modernise and streamline frequently used features across many customer disciplines. The drawing format for this release continues to be AutoCAD 2018. For developers, this is an API-breaking release.

Streamlined Trim and Extend Option

Instead of having to first select boundaries for the Trim and Extend commands, the default Quick mode selects all potential boundaries by default. Other effects include the following:

  • After you start the TRIM or EXTEND commands, simply select the objects to be trimmed or extended.
  • The default options for selecting the segments to be trimmed or extended are individual selection, freehand selection and two-point fence selection.
  • Start a freehand selection by holding down the left mouse button and dragging the cursor through one or more objects.
  • Start a fence selection by clicking two points that define a segment crossing through the objects.
  • Selected objects that cannot be trimmed are deleted instead.

For example, it's not apparent in the illustration below whether the two wall lines continuing upward and the two lines blocking the doorway are either individual line segments and need to be erased, or part of longer lines that need to be trimmed. Trimming with Quick mode, using a freehand selection for the wall lines and two fence points for the doorway, trims or erases the objects as required.


Likewise, extending objects is also faster and more convenient. In the following example, a doorway is being closed up and a wall is being lengthened.


When using TRIM with boundaries that include hatches, the trim and Shift+trim operations in Quick mode use only the boundaries of hatches, not the hatch geometry itself. For example, in this trim operation, rolling over the object that crosses the hatch object highlights the portion to be trimmed and selecting the object trims it as shown. The internal hatch geometry is excluded from the trim operation.


This behaviour is controlled by the TRIMEDGES system variable.

Note: We think you'll like the Quick mode better, but if you want to restore the previous default trim and extend behaviour, use the TRIMEXTENDMODE system variable.

Changed Commands

EXTEND - Extends objects to meet the edges of other objects.

TRIM - Trims objects to meet the edges of other objects.

New and Changed System Variables

TRIMEDGES - Controls whether trimming and extending to hatches with Quick mode is limited to the edges of the hatches or includes the objects within hatch patterns.

TRIMEXTENDMODE - Controls whether the TRIM and EXTEND commands use streamlined inputs.

Revcloud Enhancements

Revision clouds now include a single value for their approximate arc chord lengths, the distance between the endpoints of each arc segment.


The first time a revision cloud is created in a drawing, the size of the arcs are determined based on percentage the diagonal length of the current view. This ensures that the revision cloud starts at a reasonable size.

You can change the arc chord length of a selected revcloud object either in the Properties palette, from its shortcut menu, or with the new REVCLOUDPROPERTIES command. The REVCLOUDPROPERTIES command also updates other properties such as colour and layer for the revision cloud.

When a revision cloud object is selected, the Properties palette now displays Revcloud as the object type instead of Polyline. Revclouds are still basically polylines, but they have an additional arc property and the option to switch between grip styles (REVCLOUDGRIPS system variable).

New Commands

REVCLOUDPROPERTIES - Controls the approximate chord-length for the arcs in a selected revision cloud.

Changed Commands

REVCLOUD - Creates or modifies a revision cloud.

New and Changed System Variables


Break Objects at a Single Point

With the new BREAKATPOINT command, the Break at Point tool on the ribbon can now be repeated by pressing Enter. This command directly separates a line, arc, or open polyline into two objects at a specified point.


New Command

BREAKATPOINT - Breaks the selected object into two objects at a specified point.

Measure Geometry Option: Quick Measure

The Quick option of the MEASUREGEOM command now supports extracting areas and perimeters from within enclosed areas in a 2D drawing.

Clicking within a closed area highlights it in green and displays the calculated values in the Command window. If you use Shift+click to select several areas, the cumulative area and perimeters are calculated. The perimeters of enclosed islands as shown in the following illustration are also included.


Shift+click also deselects areas. To clear the selected area, simply move the mouse a small distance.

Ribbon Access

Home tab > Utilities panel > Measure/Quick.


Changed Commands

MEASUREGEOM - Adds the Quick option for real-time measurements of dimensions, distances, angles and areas.

New System Variables


Drawing History Support (Subscription Benefit)

While BAK files preserve a single, previously saved version of a drawing file, drawing files that are saved to OneDrive, Dropbox and Box cloud storage maintain previous versions of the DWG files that you store on their servers. The Drawing History feature provides a way to compare your current drawing with previous versions of that drawing. You can choose which version to compare from the Drawing History palette.

Note: The cloud storage provider that you choose sets the number of versions stored and manages their expiration dates.

When you're signed into your Autodesk Account, a notification appears the first time you access a drawing saved in your OneDrive, Dropbox or Box account. For example, if you previously saved a drawing to your Dropbox account, the following notification displays:


When you sign in, the Drawing History palette displays with a list of any previous versions of that drawing.

In the Drawing History palette, you can filter the versions listed by a date range, by a user name, or by a specified minimum time increment between versions.


You can use the Drawing Compare feature to compare the current version of a drawing with any of the previous versions in the drawing history. This capability is especially useful if several people have access to a drawing file and you need to see what's changed.


The Compare control opens the Drawing Compare feature to identify geometric or text differences between the versions. See About Comparing Differences Between Drawings for more information.

Ribbon Access

View tab > History panel > DWG History.


New Commands

DWGHISTORY - Opens the Drawing History palette, which displays a version history of the current drawing as maintained by a supported cloud storage provider.

DWGHISTORYCLOSE - Closes the Drawing History palette.

New and Changed System Variables

DWGHISTORYSTATE - Reports whether the Drawing History palette is open or closed.

Graphics Performance

The speed of panning and zooming in 2D has been enhanced with a technique that takes advantage of objects with similar properties and another technique that displays appropriate levels of detail at different levels of magnification.

When panning and zooming in real time in 2D, AutoCAD-based products automatically perform regeneration operations as needed. Normally, this operation is not noticeable except in very large drawings. In those cases, you might want to prevent panning or zooming operations that would otherwise regenerate the drawing by turning off the RTREGENAUTO system variable.

When working with 3D models, navigation generates higher or lower fidelity graphical representations of the 3D geometry in some circumstances. The program's responsiveness when using 3D orbit, pan, and zoom operations has improved significantly by making use of multi-core processors. This improvement is most noticeable on complex 3D models using visual styles that render curved surfaces.

New System Variable

RTREGENAUTO - Controls automatic regeneration in real-time panning and zooming operations.

Blocks Palette Enhancements

The enhanced Blocks palette allows you to access the blocks in a drawing anytime and anywhere. Use your Autodesk account with Autodesk Drive or any leading cloud storage provider to get quick and anytime access to your recent blocks and block library drawings.

The Recent tab of the Blocks palette displays snapshots of the recently inserted or created blocks in the current drawing. You can sync the recent blocks in a drawing to a cloud storage location and access them from any device--desktop, web or mobile. Click Sync Your Blocks, sign in to your Autodesk account and then specify a cloud storage location to start syncing your blocks.


The Sync Your Blocks option may not display in the Blocks palette if there are already recent blocks in your current drawing, or you did not use the Blocks palette to sign in to your Autodesk account.


In this case, you can change the recent blocks folder location in the Files tab of the Options dialog box and specify a cloud storage location to sync your blocks.


The Other Drawings tab of the Blocks palette has been renamed to Libraries tab. You can now specify a folder, a drawing file or any block definition stored in a drawing to insert as a block in the current drawing. The Libraries tab includes a drop-down list that displays the 5 most recently used block libraries (folder or drawing file) for faster access.


New and Changed Commands

-INSERT - Adds the Explode and Repeat command line options for inserting blocks and drawing files.

-INSERTCONTENT - Inserts a drawing or block into the current drawing. This is similar to the -INSERT command.

New System Variable

BLOCKSRECENTFOLDER - Sets the path where the recently inserted or created blocks are stored.

XREF Compare

The primary enhancement to the Compare feature is that you can now compare and see the changes made to the drawing file that's attached as an external reference (xref) in the current drawing. Any changes to the referenced drawing or a compared drawing are highlighted using revision clouds.


If a referenced drawing has changed, a balloon message is displayed in the lower-right corner of the application window (the status bar tray). Click the link in the balloon message to reload the modified xref or compare the changes. You can also compare the xref changes in the External References palette.

New Commands

XCOMPARE - Compares an attached xref with the latest state of the referenced drawing file.

XCOMPARECLOSE - Closes the Xref Compare toolbar and ends the comparison.

XCOMPARERCNEXT - Zooms to the next change set of the xref comparison result.

XCOMPARERCPREV - Zooms to the previous change set of the xref comparison result.

New System Variables

COMPARESHOWCONTEXT - Controls the visibility of objects that are not used in the xref comparison.

XCOMPAREBAKPATH - Specifies the path where the backup xref file is stored.

XCOMPAREBAKSIZE - Sets the size of the folder where the backup xref file is stored.

XCOMPARECOLORMODE - Switches the visual effect of objects in the host drawing during an xref comparison.

XCOMPAREENABLE - Enables the comparison between an xref and the referenced drawing file.

Security Enhancements

Using both internal testing and third-party assessments and audits, the AutoCAD Security team continues to harden AutoCAD-based products against emerging cyber threats and to maintain compliance with current standards and best practices.

AutoLISP Improvements

Improvements have been made to AutoLISP and DCL in AutoCAD 2021. These improvements include:

  • Cross-platform development with Microsoft Visual Studio (VS) Code
  • Unicode support

Changed Command

VLISP - Displays the AutoLISP development environment.

New System Variable

LISPSYS - Controls the default AutoLISP development environment started with the VLISP command.

AutoLISP Extension for Microsoft Visual Studio (VS) Code

A new AutoLISP extension was released for use with VS Code that allows you to edit and debug AutoLISP (LSP) files with AutoCAD.


Using the AutoLISP extension, you can:

  • Create and modify LSP files using features such as Autocomplete and Code Snippets
  • Format all or selected code statements in a LSP file
  • Add watches and breakpoints while debugging a LSP file
  • Execute AutoLISP code statements and AutoCAD commands in the Debug Console

Note: Disable any other AutoLISP related plug-ins that you might have previously installed.

Get Started:

AutoLISP Unicode Support

Prior to AutoCAD 2021, AutoLISP didn't fully support Unicode characters. Many functions related to working with strings only supported the multibyte character set (MBCS) which caused problems with functions that relied on knowing the length of a character or that returned the length of several characters in a string. You can learn more about the changed functions related to Unicode character support in the New and Changed AutoLISP Functions Reference (AutoLISP) topic.

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