Trying to wrap my head around this

Hi there,

I set about an exercise to reduce the size of a SketchUp file in order to get it to run a bit more efficiently in Layout.

My master file is 22.2MB.

I did a save as and then set about reducing the size of this new “Clean” file, by merging groups/components using Solid Inspector and Outer Shell Solid Tool, getting rid of unnecessary geometry and running the CleanUp extension on various things.

As I made progress, I noticed SketchUp was seriously beginning to lag. I isolated the groups/components that I was working on and hid everything else but SketchUp was still crawling along!

I decide to save and back out. Baring in mind, I had not introduced any new geometry into the “Clean” model and was actually deleting geometry out of this file.

The “Clean” file is somehow 89.9MB!?

Has anyone encountered this before?

I have used Scenes to ensure I am saving both files in the same state. Does the amount of geometry on screen when the file is saved affect the file size?


Have you used Purge at all?


Images (for watermarks, textures, etc.) can often be a major contributor to .SKP file size.

Geometry (edges and faces) will add up in file-size if there are a lot of them. Using components or un-opened groups can reduce file size significantly. The .SKP file will contain only one copy of a component or un-opened group, even if there are many instances of that component or un-opened group in the model. (When a group is opened, that instance of the group becomes a unique copy, thus adding more geometry to the model.) Each instance of a component or un-opened group has a relatively small contribution to the file size (instance name, transformation matrix, etc.).

If you had two instances of a given component, and exploded+New Instance’d them into one overall new component, that would increase the file size because the new overall component has all of the geometry from the original pair components (i.e., twice as many edges and faces as one of the original components).

The definition of the original unexploded component will still be in the model (contributing to file size), unless as @Box mentioned a purge has been done to delete the now-unused original component definitions from the model.

Also, outer shell may increase edge and face counts because it must make a continuous surface enclosing the originals. This involves an operation much like intersect faces with, which generates new edges and faces.