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How to Purge in SketchUp — What Purge Unused Removes
Purge Unused deletes what your SketchUp file still carries but no longer uses: component definitions, materials, styles and tags left behind by imports and deletions. It is the quickest fix for a file that is heavy for no visible reason — and the most over-sold one, because purging never removes an edge or a face that is still in use, so it cannot make a high-poly model lighter. Below: how to purge in SketchUp (there are three places, not one), exactly what each purge removes, the one case where purging costs you data, what changed in SketchUp 2025 and 2026, and what to do when the file is still heavy after a purge.
How to purge in SketchUp
SketchUp’s own help gives the path in one sentence: “The easiest way to remove unwanted entities from a model is the Purge Unused function in the Statistics section of Model Info.”
- Open Window > Model Info.
- Open the Statistics tab.
- Click Purge Unused at the bottom of the window.
That one click purges “any unreferenced components, tags, styles, and materials from the model” — all four classes in one pass.
Purging one asset type at a time
The all-at-once button is not your only option, which matters when a file deliberately carries a material library or a spare style:
- Materials: “Select In Model from the list of collections and click Details. From the available options select Purge Unused.”
- Styles: click the Details arrow next to the Styles Collections drop-down and choose Purge Unused. “SketchUp removes all styles in the In Model styles that are not actually used in your model.”
- Tags: the Tags panel Details menu has Purge, which “Deletes all tags not assigned to an entity.”
- You can also “delete components, tags, and materials one at a time” from their panels — with the caveat in the next section.
SketchUp’s cleanup guide also gives an order when you do it by hand: components and subcomponents first, then tags, then materials.
What Purge Unused removes — and what it never touches
The word that decides everything is unreferenced. A purge walks the file’s definition lists and drops entries nothing points at:
- Component and group definitions that are no longer placed anywhere in the model.
- Materials that are not painted on any face or edge. These are usually the heaviest single win, because an imported material carries its texture image with it.
- Styles you clicked while working. “Your In Model style collection can contain styles that are not actually used in your model.”
- Tags (what older SketchUp versions called Layers) with nothing assigned to them.
What survives every purge, by definition:
- Anything still referenced, visible or not. A material painted on one face you cannot see counts as used. A component definition that only exists nested inside a component you do use is referenced, so it stays — that is not a failed purge, it is a correct one.
- All geometry in use. Purging removes no edges and no faces, so the triangle count of your model is exactly the same before and after. If the weight is in the mesh, purge is the wrong tool — see the last two sections.
- Textures on materials that are in use, at their original resolution. Purge deletes whole unused materials; it never re-encodes an image.
This is also why deleting one asset by hand is not equivalent: “Deleting an entity this way will not take any of its materials, subcomponents, and tags with it.” SketchUp’s guide tells you to “Repeat process for any subcomponents that were left behind” — so if you clean up manually, run the purge afterwards, or check the In Model lists a second time.
Why the unused assets are there at all
Nothing is broken. SketchUp’s performance guide states the behaviour plainly: “Your model stores all the components, styles, and materials you’ve added while modeling even after you’ve erased or replaced them.” Two workflows fill a file fastest:
- Importing and copying. Pulling a model in from 3D Warehouse or pasting geometry from another file brings that source’s component definitions, materials and tags along, whether or not you keep the geometry.
- Trying things out. Every style you clicked to look at, and every material you loaded to test, stays in the In Model collection until something removes it.
The one risk nobody mentions: a purge is not free
The old advice that purging is “completely safe” is wrong in one concrete way, and SketchUp’s own developer documentation is the one that says so. The API reference for the purge call carries this caution: “Silently purging can cause data loss. The user may have deleted the last instance but intend to place new ones later. Don’t purge without the user’s knowledge and approval.”
In practice: the definition of that door handle you deleted five minutes ago, planning to re-place it from the Components panel, is gone after a purge. Your placed geometry is untouched — the file’s own asset library is not. If you keep materials or components in a file as a working palette, purge the classes you mean to purge from their panels rather than clicking the global button out of habit.
SketchUp 2025 and 2026: the purge prompt moved
- SketchUp 2025 added the reminder: “To help keep model file sizes manageable, a new optional reminder will appear by default any time you save your model asking if you would like to purge unused assets.” You dismiss it with Don’t Ask Again. The release notes tie it to the new Photoreal Materials, which are larger files than previous material sets.
- SketchUp 2026 reversed the default and added control: “The Purge Unused reminder seen when you save a model will now be off by default. You can still control this reminder in Preferences.” Better still: “When switched on, you can now control exactly what you want to purge, helping to make sure you aren’t purging useful assets. Purge Unused also appears in the Edit menu and can be assigned a shortcut, so that you can purge what you want, when you want.”
- The same 2026 notes report that “The time required to purge unused tags has been drastically reduced” — relevant if you work with imported CAD files that arrive with hundreds of tags.
So on 2026 the answer to “where is purge” is no longer only Model Info: bind it to a key and it becomes a one-second habit.
One-click purge with the 3dshouse Dynamic plugin
- Click the
button in the 3dshouse Dynamic plugin panel and it purges component definitions, materials, styles and tags in one go, wrapped in a single undo step — no Model Info dialog, no four separate panels. - Being precise about what it is: it calls SketchUp’s own four purge functions, once each. It does not loop or dig deeper than the native purge does< The value is the shortcut, not extra cleaning power.
- The panel’s stronger “purge all” action first erases every hidden instance in the model and then purges. That one does delete geometry, so it is not the same safe operation — use it only when you know the hidden objects are junk.
button in the Purged and the file is still heavy? Then it is the geometry
Purge Unused only ever removes assets nothing uses. When a file stays heavy — or stays laggy to orbit, which is a different symptom with the same cause — the weight sits in geometry you are using. SketchUp’s performance guide names it: “The more edges, faces, and materials you have in a model, the more resources SketchUp needs to use”, and “The more visible geometry the slower SketchUp will run.” Its advice for that is to model leaner up front: “try to use the minimum number of polygons required to communicate your design”, and “Reducing segments on arcs and circles is the easiest way to reduce your polygon count.”
That advice does not help with a model you did not draw. Downloaded furniture, scans and mesh imports arrive with their triangle count already baked in, and it is usually one component that accounts for most of it — an upholstered sofa, a plant, a car. To fix that you have to reduce the mesh itself, which is what Decimify does inside SketchUp: select one group or component, drag a reduction slider with the result live in front of you, then commit it back. Two behaviours worth knowing before you try it:
- The commit refills the component definition in place, so every instance of that component in the model updates at once, and the whole write is a single Edit > Undo.
- Reduction is per sub-mesh, not a scene-wide budget: 50% on a group of ten objects gives each object 50%.
- It writes one SketchUp face per triangle and softens interior edges by angle (90° by default); there is no coplanar merge, so the result comes back triangulated.
- If the slider refuses to reduce a textured model — typical of heavy upholstery and 3D Warehouse assets, where UV is pinned per face — turn Maintain UV off in Settings and the session rebuilds. The app tells you when that is the limit.
Decimify needs SketchUp 2022 or newer and installs as an .rbz through Extension Manager. There is also a browser version that simplifies GLB and STL files before they ever reach your model; the mesh is processed on your machine and never uploaded. Both surfaces are one licence: free covers every feature at every reduction level with a free 3dshouse account, metered at 3 exports or commits per UTC day; Pro removes the limit for $30 one-time.
Which cause of a heavy file needs which tool
This is the whole decision, in four lines:
- Unused components, materials, styles, tags → Purge Unused (Model Info, the panels, the Edit menu on 2026, or the one-click button above).
- Stray edges, duplicate faces, subdivided coplanar surfaces, hidden junk → a cleanup extension. Thomas Thomassen’s CleanUp³ lists exactly that work: “Erase lonely edges”, “Erase duplicate faces”, “Merge connected co-planar faces”, “Erase hidden geometry” — and “Purge unused items” too, so running it covers the purge as well. See the CleanUp³ install and settings guide.
- Too many triangles in geometry you actually use → mesh reduction. Neither purge nor cleanup will touch this.
- Curves drawn with far too many segments → redraw them with fewer, as SketchUp advises; on imported meshes there are no arcs left to edit, only triangles.
FAQ
What does Purge Unused mean in SketchUp?
It means deleting the model’s unreferenced assets: component definitions, materials, styles and tags that nothing in the model points at any more. SketchUp’s help describes the button as purging “any unreferenced components, tags, styles, and materials from the model”. It does not mean deleting geometry, and it does not compress anything.
How do I purge unused materials in SketchUp?
Open the Materials panel, “Select In Model from the list of collections and click Details. From the available options select Purge Unused.” Doing it from the panel purges only materials and leaves your components, styles and tags alone.
How do I purge unused components in SketchUp?
Window > Model Info > Statistics > Purge Unused removes component definitions that are no longer placed in the model, along with unused tags, styles and materials. A definition that is nested inside a component you still use is referenced, so it stays.
Is there a purge plugin for SketchUp?
You do not need one for purging itself — it is built in, and on SketchUp 2026 it sits in the Edit menu with an assignable shortcut. Extensions are worth it for the surrounding jobs: a one-click button in one undo step (the 3dshouse Dynamic panel), geometry cleanup such as coplanar merging and stray-edge removal (CleanUp³), or triangle reduction on imported components, which no purge tool can do.
