Model 3D .m3d
A compact universal model container, denser than glTF.
What an .m3d file holds
M3D is a small, deliberately universal model container designed as a simpler alternative to glTF for engines that would rather not carry a JSON parser. Its density comes from a header that declares the width of every index and coordinate in the file, so a model that fits in a 256-unit grid stores coordinates in a single byte each; the whole payload can also be zlib-wrapped. It carries meshes, materials, texture coordinates, a skeleton and animation, and has voxel and mathematical-shape flavours that describe geometry without polygons. The polygon mesh is what converts here.
Commonly seen in: Model 3D tooling, small engines, Minetest, Goxel.
| Data | Stored in M3D |
|---|---|
| Geometry | Yes |
| Materials and colour | Yes |
| Texture maps | Yes |
| Animation and rigs | No |
| Scene hierarchy | Yes |
| Read here | Yes |
| Written here | No |
Tested against a real file
The last sweep loaded suzanne.m3d from Model 3D reference models through the viewer on this site: 968 triangles across 1 meshes and 1 materials, in 1.9 seconds. Every format's result is on the test results page, run 2026-09-08.
Files to bring with it
Drop any referenced texture images in alongside the .m3d.
Convert M3D to another format
Every pairing has a page saying what survives the trip.
Other things to do with an .m3d file
Questions about M3D
How do I open an .m3d 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 M3D a good format to archive in?
M3D stores geometry, materials and colour, texture maps, scene hierarchy. Anything outside that list will not be in the file at all, so archive the original alongside it if the surfacing or the rig matters.
Does converting M3D 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.