STEP to GLB converter

Engineering teams design in CAD and share STEP files, but the web runs on glTF. Product pages with a 3D view, online configurators, assembly instructions, AR previews, documentation portals and trade-show screens all want a GLB. Getting one usually means exporting a mesh from CAD, importing it into Blender, fixing its scale and orientation, and exporting again. This STEP to GLB converter does all of that in one step: it reads the CAD geometry with a CAD kernel, meshes every body finely, keeps body colours, and writes a compact GLB in metres with Y up, as glTF expects.

How to convert STEP to GLB

1. Drop the .step or .stp file on the box. The CAD reader loads the first time, about 7.6 MB, and then stays in the browser's cache.
2. Check the preview. The overall size is shown in millimetres from the STEP's own unit, with the triangle count and number of bodies.
3. Press Download GLB. Each body becomes its own mesh in the GLB, with its colour from CAD.

From exact surfaces to triangles

A STEP file stores exact geometry: a hole is a cylinder with a radius, a fillet a torus or a spline. Web viewers and AR engines only draw triangles, so the surfaces have to be split into flat facets. The converter keeps every facet within 0.05% of the part's overall size of the true surface and limits the angle between neighbouring facets to about 14°, so every full circle gets at least 25 segments. Then it computes shading normals: where faces meet at more than 30°, the edge stays crisp; below that, the surface is shaded smoothly. Holes and fillets look round, while chamfers and machined edges stay sharp, which is what makes CAD parts look like real objects instead of faceted meshes.

File size

STEP files are large because they are verbose text describing every point, edge and face. A GLB is binary and stores each corner once. The demo gear on this page is 307 KB as STEP and 38.5 KB as GLB, about an eighth. For web pages, keeping models under a few megabytes matters, because visitors on phones load them over mobile data. If an assembly is large, export only the parts people need to see: internal screws, bearings and wiring often make up most of the triangles and are never visible.

Colours and bodies

CAD programs can store a colour per body or per face in the STEP file. The converter reads body colours and writes each body as a separate mesh with a matching material, so a housing in grey, buttons in black and a label area in white come out that way in the GLB. Body names from the STEP are kept as mesh names, which is useful when a configurator or a viewer needs to show, hide or recolour parts. Materials are plain colours; textures, decals and appearance libraries from CAD are not part of STEP files, so add them later in Blender if you need photo-realistic surfaces.

Units and orientation

STEP files record their unit, usually millimetres, sometimes inches. glTF always uses metres, so the converter divides millimetres by 1,000. A 50 mm gear becomes 0.05 m, which is how big it shows up in AR on a real desk. CAD uses Z as up, glTF uses Y, so the model is turned to stand the way it stood in CAD. The model is also centred and placed with its lowest point at zero, which AR viewers treat as the floor.

Using the GLB

For a product page, Google's model-viewer web component shows a GLB with one tag and adds an AR button on phones. three.js and Babylon.js load GLB directly for custom viewers and configurators. Most e-commerce platforms with 3D support, presentation tools and documentation systems accept GLB uploads. For printing the part instead, use the STEP to STL converter; for rendering in Blender, STEP to OBJ.

Updated November 2026 · How these tools work