Import DWG into SketchUp without issues

Importing at a glance

You import a DWG into SketchUp Pro via File, then Import, where you set the file type to AutoCAD files and select the DWG file. The most important step hides behind the Options button: there you set the unit. SketchUp does not read the unit from the DWG file, so without the correct choice the drawing comes in at the wrong scale.

DWG and DXF import are available in SketchUp Pro and Studio, not in the free web version. With a subscription that includes SketchUp Pro, you can import both 2D floor plans and 3D CAD geometry. Below you walk through the complete process, from preparing the file in AutoCAD to cleaning up after import, so you avoid the classic scale and performance problems.

Preparing in AutoCAD

A clean DWG imports much more smoothly than a messy file. Therefore, tidy up the drawing in AutoCAD first before you export it. That saves a lot of cleanup work later in SketchUp and keeps your model light.

• Delete layers, blocks and text styles you don't need with the PURGE command.
• Use WBLOCK to isolate only the area or layer you really want to import.
• Place the drawing close to the origin, because geometry far from the origin makes SketchUp slow.
• Explode polylines with arcs if you want to see the arcs as true segments after import.

When in doubt, save a separate, cleaned-up export version of your DWG and leave your original working drawing untouched. This way you keep your complete drawing in AutoCAD and import only what is strictly necessary into SketchUp.

Also pay attention to the DWG version you save. SketchUp reads the common AutoCAD formats, but a very old or brand new format can cause problems. In AutoCAD, save using Save As and choose a widely supported DWG format from a few years back. That way you can be sure SketchUp reads the file without complaints.

Step-by-step import

Follow these steps to bring in a DWG neatly.

1. Open your model and choose File, then Import.
2. Set the file type at the bottom right to AutoCAD files (*.dwg, *.dxf).
3. Select the DWG file but do not click Import yet.
4. Click Options and set the unit and the desired import preferences.
5. Confirm with OK and then click Import.
6. Review the summary window showing the number of imported entities and close it.

The imported drawing comes in as a single component or group, so you can move it in one go without the lines sticking to your existing model. Place it where you want it and click to confirm. The summary window is useful: if it shows zero imported entities, the layer possibly contained nothing usable or the wrong file type was selected.

The layers from AutoCAD come across as tags in SketchUp. That is handy, because you can make parts of the drawing separately visible or hidden via the Tags panel. Usually you want to model the import on the default tag (Untagged) and only use the imported tags to control what you see. Therefore, never assign geometry itself to a tag, only the groups and components containing that geometry.

Choosing the correct unit

Scaling error is the most common problem with DWG import, and the cause is always the same: SketchUp does not detect the unit itself. In the Options window you choose from Model units, millimetres, centimetres, metres, inches, feet and kilometres among others.

If you know the unit the drawing was drawn in, choose that exactly. A floor plan in millimetres you import with the Millimetres option, then it comes in at true size. If you don't know the source unit, choose Model units, because then SketchUp converts one CAD unit to one inch, or take a large unit like metres and scale the drawing manually afterwards.

After import, always check a known dimension with the Tape Measure tool. For example, measure a door that should be 900 millimetres wide. If the length is incorrect, use the Scale command, or measure the distance with Tape Measure and type the correct value directly when SketchUp asks if you want to resize the entire model. That way you get everything to the right size in one go.

Import options explained

Besides the unit, the Options window offers a few settings that determine the import quality.

• Merge Coplanar Faces: removes redundant triangulation lines within flat faces, giving you cleaner faces.
• Orient Faces Consistently: lets SketchUp orient the front of imported faces uniformly, so you don't see blue back faces everywhere.
• Preserve Drawing Origin: places the geometry at the origin from the DWG file. If you leave this off, the drawing appears close to the SketchUp origin.

For most floor plans you leave Merge Coplanar Faces and Orient Faces Consistently ticked. Only switch on Preserve Drawing Origin if you need multiple drawings to align with each other and their relative position must be correct, for example floor levels that must stack exactly above one another.

Importing 3D DWG

Not every DWG is a flat floor plan. If the file contains 3D geometry, SketchUp imports it with the same steps, but there are a few points to note. SketchUp works with faces, while AutoCAD often works with edges, solids and meshes. Solids and 3D faces usually come in cleanly, but loose edges without a closed loop remain lines without a face.

If you get a 3D import consisting of loose lines, you must close the faces yourself by tracing an edge with the Line tool so that SketchUp recognises the face. Curved surfaces from AutoCAD appear as a mesh of small faces, which makes the geometry heavy. Therefore, keep 3D imports as simple as possible and import only what you really need.

If you're unsure whether the data is 2D or 3D, view the drawing in AutoCAD first in an isometric view. That way you know beforehand what to expect in SketchUp and can choose the right cleanup strategy after import.

Common problems

The following problems are most common after a DWG import, with their solution alongside.

If geometry lies far from the origin, for example on national grid co-ordinates, SketchUp works noticeably slower and inaccuracies can arise because SketchUp calculates with limited precision far from the origin. Move the drawing in AutoCAD to near the origin before exporting.

Cleaning up after import

A DWG often contains more than you need. So clean up as soon as the import is in. Only explode the import when you really need the loose lines to create faces, because as long as everything sits in a group or component, it remains manageable.

1. Right-click the import and choose Explode if you want to edit the lines separately.
2. Create faces by tracing open contours with the Line tool.
3. Delete superfluous tags that came from AutoCAD via the Tags panel.
4. Use the Model Info window or statistics to remove unused items with Purge Unused.

Then put the usable parts into logical groups or components. If you're unsure which container is best, read when to choose components or groups in SketchUp. That saves a lot of editing time later and keeps your model neatly structured.

A handy method is to keep the import as a separate reference at the bottom and model on top of it. Place the imported floor plan on the ground (the red and green plane) and pull up your walls with Push/Pull by following the contours. This way you use the CAD drawing as a dimensionally accurate underlay without needing to edit the import itself. Lock the import if necessary so you don't move it accidentally.

File size and performance

A heavy DWG can make your SketchUp model unnecessarily large. Limit that by cleaning up already in AutoCAD: delete unused layers, blocks and text styles, and export only the layer or area you need instead of the entire drawing.

After import, use the Purge Unused command to clean up all items you are not using in one go. A lighter model opens faster, rotates more smoothly and renders more stably. Check the statistics via Window, Model Info, Statistics to see how many edges and faces your import added.

If you notice an import contains an extremely large number of lines, the drawing is probably too detailed for your purpose. A floor plan with all furniture symbols, hatching and dimension lines is heavier than you need to draw walls. Remove those details in AutoCAD or keep them on a separate, hidden tag, so your model remains workable.

If you later want to turn the drawing into a 3D model and visualise it, check beforehand that your SketchUp licence is correctly activated, because CAD import is only included in the paid versions. The official instructions can be found in the SketchUp Help Center on CAD import.