Reduce SketchUp File Size: Purge Fixes Only 1 of 5 Causes

To reduce SketchUp file size, check five causes in this order: unused definitions, high-resolution textures, dense imported meshes, stray geometry, and display load. Purge Unused fixes only the first, which is why a model often shrinks on the first purge and then refuses to get lighter: what is left is in use, and purge never touches anything that is in use.

Reduce SketchUp file size: the checklist

1. Measure. Note the .skp size on disk. Open Window > Model Info > Statistics and note the edge and face counts.
2. Purge Unused in the same pane, save, compare the size. A big drop means the cause was unused definitions and you are done.
3. Textures. File still large but the face count modest? Lower the resolution of the materials that are in use (Materials panel), and prefer JPEG to TIFF.
4. Heavy imported meshes. Face count still high after the purge? That is 3D Warehouse furniture, scans or meshes from other software. Purge cannot remove it; reduce its polygons with Decimify inside SketchUp (select the group or component, pull a slider, commit).
5. Debris. Stray edges, overlapping faces, odd errors? Run CleanUp³, and SketchUp’s Fix Problems.
6. Display only. File size normal but orbiting stutters? Turn off shadows and fog, use a plain style, hide detail with tags.

Video: purge unused entities and optimize heavy SketchUp files

Step 1: read two numbers before you change anything

SketchUp describes the Statistics pane as the one that “keeps track of all the entities your model contains”, where you also “find tools for purging unused entities and fixing some common problems”.

• File size before and after Purge Unused tells you whether the problem was unused assets.
• Edge and face counts that stay high after purging mean the problem is geometry, and no cleanup command will fix it.

Those two numbers split the problem in half and stop you installing a purge plugin for a model that is heavy because somebody dropped a 3D scan into it.

How to purge a SketchUp file: unused components, materials, tags, styles

SketchUp’s help states the mechanism: “Your model stores all the components, styles, and materials you’ve added while modeling even after you’ve erased or replaced them.” Nothing in the viewport shows them, so the file grows silently through a long session, and every model you import adds its own.
The command is Window > Model Info > Statistics > Purge Unused. Three things worth knowing:

• Repeat it until the size stops falling. SketchUp’s manual steps for removing a single component end with “Repeat process for any subcomponents that were left behind.” A second pass costs seconds.
• SketchUp 2025 asks at save time. From the release notes: “By default, a reminder will now appear when saving a file asking if you would like to purge unused assets, preventing model bloat.” It can be turned off in the General tab of Preferences. The notes also say 2025’s “new Photoreal Materials are significantly larger than the materials in previous versions”.
• A small white triangle marks a material that is in use. SketchUp: “In the Materials panel you can identify materials referenced in your model by a small white triangle.” Those are the ones purge will leave.

The one-click version of the same command is the Purge Unused tool shown in the video above.

Textures: the weight purge cannot reach

A texture painted on a face is in use, so purge leaves it alone however large it is. SketchUp publishes the figure: “A material at a 2048 x 2048 resolution is 2.4Mb. The same material at a 320 x 320 resolution is only 176K.” Its own verdict: in most models the two are functionally the same.

• Edit the material in the Materials panel and reduce its resolution. SketchUp’s advice is to “reuse materials and textures where you can, and reduce the resolution of the images you import”.
• Prefer compressed formats: “While TIFF files are high quality, they also tend to be larger files and take more resources to display. Try using an image in JPEG format instead.”
• CleanUp³’s Merge Identical Materials merges identical materials and ignores metadata attributes by default. Its tooltip warns that this metadata “Might include render engine data” (check before merging on a V-Ray or Enscape scene), and that it “Processes all materials in the model, not just the current scope”.

Heavy imported meshes: reduce polygons, where purge and cleanup stop

“Every face adds to the file size of the model”, and “the more edges, faces, and materials you have in a model, the more resources SketchUp needs to use.” Geometry that is placed in the model is in use, so purge cannot make it lighter.
Typical sources: 3D Warehouse furniture, 3D scans and meshes imported from other software. SketchUp’s advice is to note “the file size and edge count of components you import into your model”; for 3D Warehouse models those values are listed in the model’s description, so you can check before importing. For your own curves, “Reducing segments on arcs and circles is the easiest way to reduce your polygon count.”
Be exact about what a cleanup extension can do here. CleanUp³’s Merge Coplanar Faces “removes edges separating coplanar faces”, which suits imported CAD surfaces sliced into strips and does nothing for a curved sofa, where no triangles are coplanar. Reducing a curved or scanned mesh means collapsing real geometry, which is polygon reduction, not cleanup.
That is the step Decimify runs inside SketchUp: select one group or component, pull a slider, commit the result back. What matters in practice:

• The slider is a target triangle-count ratio applied per sub-mesh, not a scene-wide budget. Ten objects at 50% each get 50%.
• Committing onto the selection refills that component definition in place, so every instance of it updates at once, and the whole commit is one Edit > Undo.
• The result is written back as one face per triangle; Smooth angle (°) decides which interior edges are softened and smoothed. Reduce parts that are already meshes, not flat CAD surfaces.
• Four settings: Lock boundaries, Preserve creases, Maintain UV, Smooth angle (°).
• If the slider barely moves on a textured 3D Warehouse model, turn Maintain UV off. When a texture is pinned per face, typical of upholstery, every corner carries its own UV slot and Decimify will not reduce across them. With Maintain UV off it reduces freely and the texture is re-mapped per face.
• Free covers every feature and unlimited exports and commits with a 3dshouse account, reducing up to 30% of the faces. SketchUp 2022 or newer.

Reduce SKP file size online: what a browser can do

No browser service takes a .skp and hands back a lighter .skp. What works online is mesh level: export the heavy part, reduce it, bring it back.

• Export with File > Export > 3D Model. Choose GLTF Binary File (*.glb) to carry materials and textures, or STL for bare geometry and keep it on Binary, which SketchUp says “helps reduce the size of an STL file”. Both are built in; no extension is needed.
• Reduce it in the tab: Decimify Online accepts GLB and STL only, not .skp. It runs as WebAssembly in the page, so the mesh is never uploaded (the page and the sign-in do need internet).
• Bring the result back with File > Import, or skip the round trip and use the SketchUp extension, which reduces the selected component where it stands.

Stray, duplicate and broken geometry: CleanUp³ and Fix Problems

This weight is small, but it is what makes a model misbehave. CleanUp³ (Thomas Thomassen, version 3.4.6, free, MIT-licensed, requires TT_Lib²) works on a Scope of Model, Local or Selected, so you can clean one component instead of the whole file. Tooltips from its source:

• Erase Stray Edges: “Removes all edges not connected to any face.” On by default.
• Repair Split Edges: on by default.
• Erase Duplicate Faces: off by default; the tooltip says “Warning: Very slow!” and to use it only to correct models with overlapping faces.
• Erase Hidden Geometry (off by default), Geometry to Layer0, Merge Coplanar Faces, Merge Identical Materials, plus Smooth Edges by Angle.

The option nobody reads is the one that saves models. “Validate Results” runs SketchUp’s validation tool after cleaning; the tooltip adds “(Windows only. OSX users should run Fix Problems manually.)” Fix Problems is SketchUp’s own repair command, and it is often the real answer to odd errors that no amount of purging changes (the Statistics pane itself offers “tools for purging unused entities and fixing some common problems”). Settings and install steps: CleanUp³ setup guide.

When the file is fine and only the display is heavy

If orbiting stutters but the file size is ordinary, nothing needs deleting. From SketchUp’s performance guide:

• Fog and shadows “give SketchUp more work to do”; turn both off in the View options while you model.
• “Stick to simple styles”: keep a plain one for modelling and a heavy one for presentation.
• “The more visible geometry the slower SketchUp will run.” Park detail on tags and switch them off while you work.
• “Multiple instances of a component are lighter weight than multiple copies of an entity or group”, so copy components rather than loose geometry.

Hiding does not shrink the file. “Avoid turning off or hiding edges. This will not simplify the geometry because the edges are still there,” and “any geometry that’s hidden is still there. You just can’t see or select it.” Hiding improves performance; it does not lower the size or the face count.

Which fix for which cause

What you see	Real cause	Fix
File shrinks a lot on the first purge	Unused components, materials, tags, styles	Purge Unused, repeat
File still huge, face count modest	High-resolution textures in use	Lower material resolution; JPEG instead of TIFF
Face count huge and stays huge	Dense imports, scans, organic meshes	Reduce polygons (Decimify)
Flat imported surfaces cut into strips	Redundant coplanar edges	CleanUp³ Merge Coplanar Faces
Stray edges, overlapping faces	Leftover modelling debris	CleanUp³ Erase Stray Edges / Erase Duplicate Faces
Slow orbit, normal file size	Display load: shadows, textures, visible geometry	Shadows and fog off, plain style, hide with tags
Errors, geometry acting wrong	Invalid geometry	Fix Problems

FAQ

How do I purge a SketchUp file?

Open Window > Model Info > Statistics and click Purge Unused. It removes definitions nothing in the model uses any more: components, tags, materials and styles you added earlier, then erased or replaced. Save and compare the file size. If it still falls on a second run, repeat; if it does not move, the weight is in things that are in use (textures, geometry) and purge cannot reach it. From SketchUp 2025 a purge reminder also appears each time you save manually, unless you turn it off in Preferences.

What does purge mean in SketchUp?

Purge means deleting definitions the model still stores but no longer uses. SketchUp’s help explains that even after you delete an entity, its definition stays in the model, which it calls model bloat. Purge Unused clears that leftover. It does not remove geometry that is placed in the model, so it cannot lower your polygon count.

How do I make a SketchUp file less heavy?

Work through the causes in order: purge unused definitions, lower the resolution of textures that are really in use, reduce the triangle count of imported or scanned meshes, then remove stray edges and duplicate faces. If the file size is normal and only orbiting is slow, turn off shadows and fog and park detail on tags instead of deleting it.

Can I reduce a SketchUp file size online for free?

Not the .skp itself: no browser service reads and rewrites SketchUp’s own format. What works online is mesh reduction. Export the heavy part with File > Export > 3D Model as GLB or binary STL, reduce it in a browser tool such as Decimify Online, then import it back. The reduction runs in the page, so the mesh is not uploaded, but the page and the sign-in need an internet connection.

Is there a SketchUp file compressor or SKP file size reducer?

There is no single button, because file size is content: reducing it means removing or lowering content. Purge Unused removes unused definitions, the Materials panel lowers texture resolution, CleanUp³ erases stray edges and merges coplanar faces, and a polygon reducer such as Decimify thins a dense mesh inside SketchUp 2022 or newer. Match the tool to the cause in the table above.