What is the SKP file format?
A .skp file contains a 3D model or an element of such a model. This format is native to SketchUp software. .skp is a proprietary binary format whose specification has never been publicly released, though SketchUp SDK libraries and the C API are available to developers. Each model stored in a .skp file holds information about:
- Points,
- Edges and edge effects,
- Shading,
- Textures.
.skp files can also be used as containers to store separate models as components of a larger project. SketchUp was originally developed by @Last Software in 2000. The company was then acquired by Google in 2006; Google engineers added the ability to use .skp models inside Google Earth. Since 2012 SketchUp has been owned by Trimble Inc. SketchUp was conceived as a general-purpose 3D modelling application for commercial use, but it was quickly embraced by professionals working in architecture, interior design, engineering, and game development. Current SketchUp editions include:
- Pro - the full desktop version for professionals, with support for additional formats and plugins,
- Go - a web-based subscription tier for individual creators working on real-life projects,
- Free - a free web-only version with limited functionality, available since late 2017,
- Make - a free desktop version released in 2017, now discontinued.
The internal structure of a .skp file is version-specific; files written by a newer release of SketchUp cannot be opened by older versions. Creating, viewing, and editing .skp files is possible through the SketchUp C API and its built-in Ruby scripting environment. Files containing a backup copy of a .skp project use the .skb extension. Trimble also maintains the 3D Warehouse, an online library where users can share and download .skp models for reuse in their own projects.
Security & safety
RISK: LOWAn .skp is a data file (a 3D model), not a program, so opening one is generally safe. The one caveat: SketchUp models can carry extensions/dynamic-component scripts and you may be prompted about embedded content - only open .skp files and install SketchUp extensions from sources you trust (e.g. the official 3D Warehouse and Extension Warehouse). As with any complex parser, keep SketchUp updated, and beware look-alike "free SketchUp download" sites - get it from sketchup.com.
Format details
in a nutshellPrograms that open SKP files
Windows4 apps
SketchUp (Pro / desktop)
Paid File → Open the .skp. If it won't open, the file is from a newer version - ask the sender to 'Save As' an older version, or use SketchUp Free.
SketchUp Free (web)
Freemium Sign in at the web app, click Open, and upload the .skp - opens and edits in the browser with no install.
SketchUp Viewer
Free Open the .skp to view/orbit the model without editing - for people who don't model. 
macOS2 apps
SketchUp (Pro / desktop)
Paid File → Open the .skp; save down to an older version if a collaborator needs it.
SketchUp Free
Freemium The official browser-based SketchUp; open and edit .skp files directly, export to STL/PNG. Technical details
deep spec| MIME type | application/vnd.sketchup.skp |
| Format type | Proprietary binary, version-specific 3D model file |
| File header | UTF-16LE string "SketchUp Model" near the start of the file; no single stable public magic number - header bytes vary between format versions |
| Coordinate system | Right-handed, Z-up axis orientation |
| Default unit | Inches; configurable per model to metric or other imperial units |
| Geometry representation | Boundary representation (B-rep): planar faces, edges, and vertices; all faces must remain planar |
| Component system | Reusable component definitions with multiple placed instances; components can be nested inside other components |
| Embedded textures | PNG and JPEG image data stored directly inside the .skp binary file |
| Material system | Named materials with color, texture map, opacity, and reflectivity properties applied per face |
| Layer / tag system | Named visibility layers - renamed to "Tags" in SketchUp 2020 - for organizing and toggling geometry groups |
| Version compatibility | Each major SketchUp release writes a new format revision; files saved by a newer version cannot be opened by older releases without format conversion |
| Scripting / API | SketchUp C API and Ruby API provide programmatic read/write access to .skp geometry, entities, and attributes |
| Scene animation | Camera-position "Scenes" record multiple viewpoints and can animate transitions between them for walkthroughs |
| Backup format | Automatic backup copies of a project are saved alongside the main file using the .skb extension |
| Released | 2000 (SketchUp 1.0 by @Last Software) |
| Specification | developer.sketchup.com |
SKP conversions
Community Q&A
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