3D file format compatibility table

Which format should you use?

• 3MF to STL: What 9 Converters Kept, Dropped and Invented We sent ten test files through nine 3MF to STL converters. Simple files mostly survive. A Bambu Studio project file did not survive any of them intact, Bambu Studio included.
• How to Check a Model You Did Not Make, and Why the Order Matters One repair setting, one mesh, three apparent scales. It fixed the model, destroyed it, or did nothing. Checking size before topology is not a habit, it decides the outcome.
• What "Same Vertex" Means in an STL, and Why Four Tools Answer It Differently An STL never says two triangles share a corner. Each tool works it out its own way, so one reports a watertight mesh and another reports 5,120 shells. Measured, with the documented defaults.
• Why a 3D Model Imports at the Wrong Size: Only One Mesh Format Stores a Unit Measured across five formats: STL, OBJ, PLY and GLB write no unit of length into the file. Only 3MF does. That one missing field is why a model lands 1000 times too small or too big.
• OBJ vs STL: What Each Format Stores, and Why One Direction Costs More STL does not share vertices and OBJ does, which decides file size, what survives conversion, and why an STL converted to OBJ arrives shattered. With measured figures.
• How to Convert STL to STEP: The Route Depends on Where the STL Came From A mesh from CAD and a mesh from a scan need opposite algorithms, and using the wrong one fails predictably. Exact menu paths for FreeCAD, Fusion 360 and SolidWorks, plus which methods are paywalled.
• FBX vs OBJ: What Survives the Conversion and What Silently Does Not FBX carries rigs and animation that OBJ cannot. On PBR materials the ranking flips, and the reason is built into the FBX SDK. What each format stores, and how to convert without losing textures.
• STEP vs STL: Converting Both Ways, and Why One Direction Barely Works STEP to STL is routine. STL to STEP is not a conversion at all, it is a rebuild. Here is what each format stores, what the converters actually output, and the tool limits nobody mentions.
• What Is a GLB File? How to Open One, Look Inside It, and Convert It A GLB is a whole 3D scene in one binary file: geometry, materials and textures together. Here is how to open one without installing anything, what is actually inside, and when to convert it.
• 3MF vs STL: What Changes When You Switch, and What Nobody Warns You About 3MF carries units, colour, objects and print settings that STL cannot. It also overwrites your slicer profile, breaks between vendors, and has a real security history. All four, with sources.