Block Base Points in AutoCAD: Why 0,0 Matters and How to Change It

The base point is the point of a block that sticks to your cursor when you insert it. It decides where the block lands, the point it rotates around and the point it scales from. A well-placed base point lets you drop a block straight onto a wall corner or a grid line; a badly placed one means every insertion is followed by a MOVE.

What the base point is

A block definition is a set of objects drawn around its own origin. That origin, 0,0,0 inside the block, is the base point. When you insert the block, AutoCAD places the base point at the point you pick, then applies the rotation and scale around it. The same applies when you insert a whole DWG file as a block: the file’s base point is the value of its INSBASE variable, which is 0,0,0 unless someone has changed it with the BASE command.

Why library blocks are drawn at 0,0

If a block file has its geometry far from the origin, say at 1240,860 because it was copied out of a floor plan, the base point is still at 0,0, and the block appears far away from the cursor when you insert it. Drawing every block with its base point at 0,0 and the geometry right next to it avoids that.

That is how the blocks on cadgrid.net are made: every file has its base point at 0,0, and every drawing on the site shows it as a red dot so you can see where the block will be held. For most objects it sits at a corner of the drawing that you’d naturally snap to.

Good base points by type of block

• Furniture in plan: a back corner, the one that goes against the wall, so you can snap it to a wall corner or the intersection of two walls.
• Furniture and fixtures in elevation: a bottom corner on the floor line, so the block sits on the floor when you snap to it.
• Toilets, sinks and other fixtures: the back wall line, often at the center line of the fixture, so you can align it with the plumbing rough-in.
• People, trees and vehicles in elevation: a point on the ground line, under the figure or at the front of the vehicle.
• Doors and windows: the hinge side or the edge of the opening, so the block snaps to the jamb.
• Symbols and title blocks: the center of a symbol, the bottom left corner of a sheet border.

Changing the base point of a block already in your drawing

Option 1: the Block Editor

Double-click the block, or type BEDIT and choose it. Inside the Block Editor the origin, 0,0, is the base point. Use MOVE to move all of the geometry so that the point you want sits on 0,0 (type 0,0 as the second point), then close the editor and save the changes. Every insertion of that block in the drawing is redefined, and existing copies shift by the distance you moved the geometry, so check them after the change.

Option 2: redefine the block

Explode one copy, run BLOCK, give it the same name, pick the new base point and select the objects. AutoCAD asks whether to redefine the existing block; answer yes. This is the older way and works in every version.

Option 3: change the base point of a file

For a DWG file that you insert as a whole, open it and run BASE, then pick the new point. This sets INSBASE without moving any geometry. Save the file; the next time you insert it, the new point is the one you hold. Moving the geometry to 0,0 instead keeps the drawing tidy, and that’s how library files are usually prepared.

Base point, insertion point and grips

The insertion point is where the base point ends up in your drawing. After inserting, the block shows a grip at its insertion point: drag it to move the block, and use it as the base when you rotate or scale. If you need to snap to the insertion point of a block, use the Insert object snap.

When a block comes in with the wrong rotation or mirrored, rotate it around its insertion point with ROTATE, picking the grip as the base point; the block stays attached to the corner you placed it on.

Base points in 3D models

3D blocks work the same way, with a Z value added. For furniture, fixtures and figures the base point should sit on the floor plane, at Z = 0, so the model stands on the floor of a 3D view instead of floating above it or sinking through it. When a 3D model comes in at the wrong height, check the Z coordinate of its base point in the Block Editor before moving it in every view.

Quick checklist

1. Open a block in the Block Editor to see where its base point is: it’s the origin.
2. Put it where you’ll snap: a corner on the wall, a point on the floor line, the back wall line of a fixture.
3. Move the geometry to 0,0 rather than leaving it far away.
4. For whole files, check INSBASE or set it with BASE.