How-to guide · how to create a block in autocad
How to create a block in AutoCAD
By Sumana Kumar · Published 7 Nov 2024 · Updated 27 Nov 2025
Turning your own geometry into a reusable block is one of the highest-value skills in AutoCAD: define a symbol once and you can drop it into any drawing, edit it in one place, and keep your files small. This guide shows how to create a block with the BLOCK command for use inside the current drawing, and how to use WBLOCK to write it out as a standalone DWG for a reusable library.
We will build a simple block from start to finish, set a sensible base point and units, and then explain how to build your own block library so you stop redrawing the same furniture, fixtures and symbols.
The time saved compounds quickly. The first time you define a block it costs a couple of minutes; every time you reuse it afterward it costs seconds, and every global edit to the definition updates dozens or hundreds of instances at once. That is why experienced drafters treat block-making as core technique rather than an advanced trick — it is the single habit that most reliably speeds up production drawing.
Step 1 — Draw the geometry cleanly
Before you define a block, draw the symbol on layer 0 if you want it to take on the colour and lineweight of whatever layer you later insert it onto — this is the classic trick for flexible blocks. If you want the block to keep its own fixed colours (a logo, a coloured symbol), draw it on named layers instead.
Keep the geometry tidy: close polylines, remove stray nodes, and draw at true size in your drawing units (millimetres here). The cleaner the source geometry, the better the block behaves everywhere it lands.
Step 2 — Run the BLOCK command
Type BLOCK (or B) and press Enter to open the Block Definition dialog. Give the block a clear, descriptive name — something like 'CHAIR-TASK-600' rather than 'Block1' — so it is findable later. A good naming convention pays off across a project.
In the dialog you will set three things: the base point, the objects, and the behaviour options. We will handle the base point and objects next.
Step 3 — Set the base point and pick the objects
The base point is the handle AutoCAD uses when you insert the block — choose it deliberately. For a chair, the centre of the seat makes sense; for a door, the hinge point; for a title-block, the bottom-left corner. Click 'Pick point' and snap to your chosen handle.
Then click 'Select objects' and window the geometry that makes up the symbol. Decide what happens to the source objects: 'Retain' leaves them as drawn, 'Convert to block' replaces them with a block reference in place, and 'Delete' removes them. Most of the time 'Convert to block' is what you want.
Step 4 — Set units and finish the definition
In the Block Definition dialog set 'Block unit' to Millimeters (or whatever your drawing uses) so AutoCAD can rescale the block correctly when it is inserted into a drawing with different units. Tick 'Allow exploding' if you want the block to be explodable later, and add a short description so colleagues understand what it is.
Click OK. The block now exists in the current drawing's block table and can be inserted as many times as you like with INSERT. Edit the definition once (BEDIT) and every instance updates.
Step 5 — Use WBLOCK to build a reusable library
A block created with BLOCK lives only inside the current drawing. To make it reusable across projects, type WBLOCK (W) to write it out as a standalone DWG file. In the Write Block dialog choose 'Block' and select your block name (or pick objects directly), set the base point and units, and choose a destination folder.
Save your WBLOCKed symbols into a structured library folder — by category, like the catalogue on this site — and you can drag them onto any drawing from a tool palette or File Explorer. Over time this personal block library becomes one of your biggest drafting time-savers, and it is exactly how the downloadable blocks here are produced.
Going further with dynamic blocks
Once you are comfortable with static blocks, dynamic blocks are the next step. A dynamic block carries parameters and actions that let one block flex into many variants — a door that stretches to different widths and flips its hinge, a window that lengthens, a desk that comes in three sizes — all from a single definition. You build them in the Block Editor (BEDIT) by adding parameters (linear, flip, rotation) and the actions that respond to them.
The payoff is a smaller, smarter library: instead of twelve separate door blocks you keep one dynamic door and pull a grip to size it. For most people the right order is to master plain BLOCK and WBLOCK first, build a tidy named library, then convert your most-used, most-variable symbols into dynamic blocks. Keep naming and base points consistent across the library so every block inserts predictably, and your drawing speed climbs steadily as the library grows.
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Questions
Frequently asked
What's the difference between BLOCK and WBLOCK?+
BLOCK defines a block inside the current drawing only. WBLOCK writes a block (or selected objects) out to a standalone DWG file so it can be reused in any drawing. Use BLOCK for in-drawing reuse and WBLOCK to build a portable library.
Should I draw block geometry on layer 0?+
Draw it on layer 0 if you want the block to inherit the colour and lineweight of the layer it is inserted onto — this makes one block work in many contexts. Use named layers when the block must keep fixed colours, like a logo or a coloured symbol.
How do I edit a block after creating it?+
Use BEDIT (Block Editor) to open the block definition, change the geometry, then save. Every instance of that block in the drawing updates automatically when you close the editor.
Why set the block units when defining it?+
The block unit tells AutoCAD the real-world size of the geometry so it can rescale the block correctly when inserted into a drawing that uses different insertion units. Matching units prevents blocks inserting too large or too small.
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