Convert SKP to STL
SketchUp exports STL in two clicks. The difficulty is not the export — it is that SketchUp lets you build things that cannot exist, and a slicer will not accept them. Getting a printable STL is mostly about making the model solid first.
We cannot read .skp files. Reading one requires Trimble’s own SDK, which is a native library with no browser build, so no web tool opens the format. Export the STL from SketchUp using the steps below.
Exporting a printable STL from SketchUp
STL export is built in from SketchUp 2016 onward, including the free web version. For 2015 and earlier, install the free SketchUp STL extension from the Extension Warehouse first.
Make everything a group or component
Select the geometry → right-click → Make Group
SketchUp can only tell you whether something is solid if it is inside a group or component. Loose geometry is never reported as solid, however watertight it actually is.
Check that SketchUp calls it Solid
Select the group → Entity Info (Window → Entity Info)
If the panel says "Solid Group" or "Solid Component", the model encloses a real volume and will slice. If it just says "Group", something is open and it will not print reliably.
This one label is the single most useful thing in SketchUp for 3D printing. Check it before exporting, every time.
Fix it if it is not solid
Extension Warehouse → Solid Inspector² → install → run on the group
Solid Inspector² is free and it finds the exact problem: a hole, a stray edge, an internal face, a surface with no thickness. It highlights each one and can fix many automatically.
The most common cause is a face with no thickness. SketchUp walls are single surfaces unless you push-pulled them, and a surface cannot be printed. Push-pull every face into a real solid, or use the Solid Tools.
Export the STL
File → Export → 3D Model… → Save as type: STL File (*.stl)
In the web version it is File, Export, STL. The Options button lets you set the export units and whether to export only the current selection.
Set the export units
Options… → Export unit: Millimeters · File format: Binary
SketchUp’s default template is often in inches or feet, and an STL cannot record which. If the units here do not match what the slicer expects, the part arrives at the wrong size.
This is the most common SketchUp export mistake, because the model looked correct in SketchUp — where the units are known — right up until it left.
Check the result before slicing
(in any converter on this site)
Drop the STL in and look at the measured dimensions and the open-edge count. Zero open edges means solid. A non-zero count means Solid Inspector missed something, or something was outside the group you checked.
Why SketchUp models are so often unprintable
SketchUp is a surface modeller. When you draw a wall, you get a surface with no thickness — a plane in space. That is completely reasonable for architecture, which is what SketchUp is for, and completely unprintable, because a printer makes solid objects and a surface has no inside.
The word SketchUp uses is Solid, and it means something precise: a group or component whose surfaces form a closed volume with no holes, no stray edges and no internal faces. Entity Info tells you whether you have one. If it does not say Solid, a slicer will do something unpredictable.
The other frequent problem is internal faces. Drawing over an existing face, or joining two boxes that overlap, leaves faces inside the volume that no longer bound anything. They are invisible in normal shading and they stop the group being solid.
Reversed faces are a third. SketchUp faces have a front and a back, shown as white and blue-grey. A model with back faces pointing outwards can still be solid, but many downstream tools misread it. Right-click and Reverse Faces, or use View, Face Style, Monochrome to see which is which.
Solid Inspector² finds all of these, is free from the Extension Warehouse, and is the single most useful thing to install if you print from SketchUp.
The scale problem, which has a SketchUp-specific cause
SketchUp’s default templates are frequently imperial — the Architectural template works in inches and feet — and a great many models are built in one without the author thinking about it, because the dimensions shown on screen are correct and readable.
An STL cannot record a unit. So a model that is 4 inches wide exports as the number 4, and a slicer reading millimetres makes a part 4 mm wide. That is the 25.4 times too small case, and it is the most common SketchUp printing failure after the solid problem.
The export units dropdown is where to fix it: set it to Millimeters and SketchUp converts on the way out. Alternatively start from the metric template, which is Window, Model Info, Units in the desktop version.
Whichever you do, check the exported file somewhere the units are measured rather than assumed. Every converter on this site shows the measured width, depth and height, which settles it in a couple of seconds.
The web version, and which one you have
SketchUp Free runs in a browser and exports STL directly — File, Export, STL. It cannot install extensions, so Solid Inspector² is not available there, and the solid check is limited to what Entity Info reports.
SketchUp Pro on the desktop has the full Extension Warehouse, the Solid Tools for boolean operations, and more control over the export. If you print from SketchUp regularly, the Solid Tools alone are worth having — they are the reliable way to turn overlapping shapes into one clean solid.
SketchUp Make 2017 was the last free desktop version and still works; it has the Extension Warehouse, so Solid Inspector² runs on it, but not the Solid Tools, which were always a Pro feature.
Where we can actually help
Once you have the STL, converting it to 3MF here records the units in the file so the size cannot be misread again. SketchUp also exports COLLADA, and if you have a .dae instead, that converts here directly.
Questions
- My slicer says the SketchUp model is not watertight.
- Check Entity Info says "Solid Group" or "Solid Component". If it does not, install Solid Inspector² from the Extension Warehouse — it finds the exact hole, stray edge or internal face and fixes most of them automatically.
- Why is my part 25 times too small?
- The model was built in inches and the slicer read millimetres. Set the export unit to Millimeters in the STL export options, and check the measured size in a converter afterwards.
- Do I need an extension to export STL?
- Not since SketchUp 2016 — it is built in, including in the free web version. For 2015 and earlier, install the free SketchUp STL extension from the Extension Warehouse.
- What does "Solid" actually mean in SketchUp?
- A group or component whose faces form a completely closed volume: no holes, no stray edges, no internal faces. Only groups and components can be solid — loose geometry never reports as solid, however watertight it looks.
- Can I open a .skp without SketchUp?
- Not in a browser. Reading the format needs Trimble’s own SDK. SketchUp Free runs in a browser and will open one, which is the practical answer if you do not have the desktop version.
Where to go next
Related guides
Tools that do part of this here
About these formats
Checked against current software versions on 2026-09-11