How-to guide · how to rename a block in autocad

How to rename a block in AutoCAD

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By Sumana Kumar · Published 25 Mar 2024 · Updated 16 Mar 2025

A block's name is more than a label — it is the key AutoCAD uses to track every instance, so renaming a block has to be done through the right command, not by retyping anything. The tool is RENAME, and it changes a block's name safely while keeping all of its references intact, so nothing in your drawing breaks.

Renaming matters most when you inherit drawings. Downloaded and imported blocks often arrive with unhelpful names like 'A$C2F19', '_Block17' or a foreign-language description, and a tidy, consistent naming scheme makes a library searchable and a drawing professional. This guide shows how to rename one block, how to rename many at once, why you should never explode-and-redefine just to rename, and what names AutoCAD will not let you change.

We will use the RENAME dialog as the main route because it handles blocks, layers, text styles and more from one place.

Step 1 — Open the RENAME dialog

Type RENAME (or REN) and press Enter to open the Rename dialog. On the left, under 'Named Objects', choose 'Blocks'. The middle panel then lists every block defined in the current drawing. This single dialog is also where you rename layers, dimension styles, text styles, layouts and more, so it is worth knowing well.

Scroll or click to find the block you want to change. If the drawing has dozens of imported blocks with cryptic names, this list is your map of what is actually defined — even blocks not currently placed in the drawing will show here.

Step 2 — Pick the block and type the new name

Click the block name in the 'Items' list. Its current name drops into the 'Old Name' field. Type the new name into the 'Rename To' box and click the 'Rename To' button to apply it. The change is immediate and every reference to that block updates to the new name automatically — no instances are lost, moved or altered.

Use a clear, descriptive name: something like 'CHAIR-TASK-600' or 'DOOR-SINGLE-800' beats 'Block12'. A good name encodes the type and a key dimension so the block is findable later by INSERT, by the block dropdown and by anyone else opening the file.

Step 3 — Rename in bulk with wildcards

If you have inherited a pile of badly-named blocks, the Rename dialog supports wildcards for batch work. Type a pattern with an asterisk in 'Old Name' (for example 'IMPORT*') and a replacement in 'Rename To' to retarget a group, or use the pattern to filter the list down to the blocks you mean to fix.

For heavier cleanup across many drawings, a renaming tool or LISP routine can apply a convention en masse, but for a single drawing the wildcard support in RENAME usually covers it. The goal is a consistent prefix-and-detail scheme so blocks sort together and read at a glance in any block list.

Why not just explode and re-block?

It is tempting to 'rename' a block by exploding an instance and redefining it under a new name — don't. That route destroys the link to every other instance, leaves you re-selecting geometry, and risks subtly changing the base point or the geometry in the process. RENAME is non-destructive: it changes only the name in the block table while every reference quietly follows along.

The one time you genuinely want a new definition rather than a rename is when you want a renamed copy that can diverge from the original — and for that the right tool is BSAVEAS in the Block Editor, which saves the current block under a new name as a true second definition. Renaming and copying are different intents; use RENAME to fix a name, BSAVEAS to fork a variant.

Names AutoCAD won't let you rename

A few names are reserved. You cannot rename layer 0, the Defpoints layer, the Continuous linetype, the Standard text and dimension styles, or the model/layout tabs through RENAME — these are baked in. Anonymous blocks (names that begin with '*', generated by hatches, dimensions and dynamic-block variants) also cannot and should not be renamed; they are managed by AutoCAD internally.

If RENAME refuses a name, check for these reserved cases, and check you are not trying to give two blocks the same name — names must be unique within the block table. Also avoid characters AutoCAD dislikes in names; stick to letters, numbers, hyphens and underscores for maximum portability across programs that read DWG.

Cleaning up an imported drawing's block names

Renaming really shines when you adopt a downloaded library or a consultant's drawing. Imported files frequently carry blocks named in another language, or auto-generated strings that mean nothing, or duplicates that differ only by a numeric suffix. Working through RENAME and applying one consistent convention turns that mess into a usable kit you can actually search.

A practical convention is TYPE-DETAIL-SIZE: 'WC-CLOSECOUPLED', 'TREE-BROADLEAF-PLAN', 'TABLE-REC-4P'. Group by leading word so related blocks cluster in the list, and keep sizes in millimetres in the name where they help. Do the renaming once, save the cleaned drawing as a template or library file, and every future project inherits the tidy names. Pair this with a PURGE to drop blocks you renamed but never actually need, and the drawing's block table becomes a clean, professional asset rather than a dumping ground.

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Questions

Frequently asked

Will renaming a block break its instances?+

No. The RENAME command changes only the name stored in the block table, and every reference updates to the new name automatically. All instances keep their position, scale and rotation — nothing is lost or moved by a rename.

How do I rename several blocks at once?+

The Rename dialog supports wildcards. Enter a pattern with an asterisk in 'Old Name' to target a group of similarly-named blocks, then a replacement in 'Rename To'. For large multi-drawing cleanups, a LISP routine or rename tool can apply a convention across many files.

Why can't I rename a particular block?+

Some names are reserved — layer 0, Defpoints, the Standard styles, the Continuous linetype — and anonymous blocks whose names start with an asterisk are managed by AutoCAD internally and can't be renamed. Also, two blocks can't share a name, so a clash will be rejected.

Should I explode a block to rename it?+

No — exploding destroys the link between instances and loses the block entirely. Use RENAME to change a name non-destructively, or BSAVEAS in the Block Editor if you actually want a separate renamed copy that can differ from the original.

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