Direct3D X File .x
Microsoft’s DirectX mesh format. Skinned characters from the DX era.
What an .x file holds
The .x file was Microsoft’s model format for DirectX, shipped with the SDK and used by a generation of Windows games and hobbyist engines. It comes in both text and binary flavours and carries meshes, materials, bone hierarchies and skinning weights. Microsoft retired it along with the DirectX SDK, but a great deal of tutorial-era and indie content is still stored in it.
Commonly seen in: DirectX games, Blitz3D, Irrlicht, legacy Windows engines.
| Data | Stored in X |
|---|---|
| Geometry | Yes |
| Materials and colour | Yes |
| Texture maps | Yes |
| Animation and rigs | Yes |
| Scene hierarchy | Yes |
| Read here | Yes |
| Written here | No |
Tested against a real file
The last sweep loaded Testwuson.X from Assimp test models with its 4 sidecar files through the viewer on this site: 3,732 triangles across 1 meshes and 1 materials, in 2.9 seconds. Every format's result is on the test results page, run 2026-09-08.
Convert X to another format
Every pairing has a page saying what survives the trip.
Other things to do with an .x file
Questions about X
How do I open an .x file?
Drop it into the viewer on this site and it opens in the browser, with the scene tree, the materials and the mesh statistics. Nothing is uploaded. If you want it in another program instead, convert it to GLB, which almost everything reads.
Is X a good format to archive in?
X carries geometry, materials, textures and animation, so an archive copy keeps nearly everything. The usual caveat applies: a format is only as future-proof as the readers that exist for it, and .x is well served.
Does converting X lose quality?
Geometry is copied vertex for vertex, so the shape does not degrade. What gets lost is whatever the target format has no field for: convert to STL and the materials go, convert to OBJ and the animation goes. The comparison table on each converter page says exactly which.
Formats that hold the same things
Or go back to the full format reference.