Roblox Model .rbxm
Roblox models. Every built-in part comes through; meshes do not.
What an .rbxm file holds
An .rbxm holds a Roblox instance tree in a chunked binary container, with each property stored as one column across every instance of a class rather than object by object, and the payloads packed with LZ4 or Zstandard. Roblox builds are assembled from boxes, spheres, cylinders and wedges with a size, a position and a colour, and all of that reconstructs exactly, hierarchy included. What cannot is a MeshPart or a CSG union: those store an asset id pointing at Roblox’s own servers rather than any geometry, so they come through as empty nodes and are reported.
Commonly seen in: Roblox Studio, Rojo, Roblox asset pipelines.
| Data | Stored in RBXM |
|---|---|
| Geometry | Yes |
| Materials and colour | Yes |
| Texture maps | No |
| Animation and rigs | No |
| Scene hierarchy | Yes |
| Read here | Yes |
| Written here | No |
Tested against a real file
The last sweep loaded parts-1000.rbxm from rbx-dom benchmarks through the viewer on this site: 12,000 triangles across 1,000 meshes and 1 materials, in 2.4 seconds. Every format's result is on the test results page, run 2026-09-08.
Convert RBXM to another format
Every pairing has a page saying what survives the trip.
Other things to do with an .rbxm file
Questions about RBXM
How do I open an .rbxm 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 RBXM a good format to archive in?
RBXM stores geometry, materials and colour, 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 RBXM 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.