STL vs OBJ vs FBX vs STEP: Best Export Format for Revit, Rhino & Blender (+ Watertight Guide)

When working in 3D design environments like Revit, Rhino, or Blender, exporting your model in the right file format can significantly impact how it performs across software, whether for 3D printing, rendering, simulation, or BIM integration. The four most common file types—STL, OBJ, FBX, and STEP—serve different purposes, and choosing the wrong one can lead to data loss, bloated files, or failed imports. Here's a detailed, intent-driven comparison of when to use each—and how to ensure your exports are watertight.

STL (Stereolithography): Best for 3D Printing

Use STL when:

Pros:

Cons:

  • No support for textures, colors, or materials.

  • Only supports triangular meshes.

  • Lacks scale metadata—units must be clarified manually.

Watertight Tip:
 STL exports are notorious for producing non-manifold edges. Always run a mesh repair check in tools like Netfabb, Meshmixer, or Blender’s “3D Print Toolbox” before sending to print.

OBJ (Wavefront OBJ): Best for Mesh Editing & Rendering

Use OBJ when:

  • You need to export models for rendering, game engines, or mesh editing.

  • Preserving UV maps, textures, and normals is essential.

Pros:

  • Retains vertex color, texture coordinates, and normals.

  • Compatible with many 3D graphics and animation tools.

  • Works well for high-fidelity visual projects.

Cons:

  • Larger file size than STL.

  • May not be supported natively by CAD or BIM software.

  • Doesn’t handle parametric or hierarchy data well.

Watertight Tip:
 While OBJ can carry detailed surface information, it still lacks parametric intelligence. Ensure “Merge Vertices” is enabled on export to prevent hidden cracks in joined surfaces.

FBX (Filmbox): Best for Animation & Game Engines

Use FBX when:

  • Your model includes animation, rigging, or hierarchical scene data.

  • You're importing/exporting between Blender, Unity, Unreal, or 3ds Max.

Pros:

  • Supports full scene structure, including cameras, lights, animations.

  • Preserves material and texture assignments.

  • Industry standard for game development and VFX pipelines.

Cons:

  • Proprietary format (Autodesk)—interoperability can be flaky.

  • Can be unnecessarily complex for static models.

  • Export/import inconsistencies across versions.

Watertight Tip:

FBX isn’t usually used for manufacturing, but if you're converting animated assets into a mesh, ensure modifiers are applied and the final geometry is closed before export.

STEP (Standard for the Exchange of Product Data): Best for CAD & BIM

Use STEP when:

  • You’re exporting parametric models or BIM elements.

  • You need to preserve solid geometry, assembly hierarchies, and accurate units.

Pros:

  • Ideal for engineering workflows and manufacturing.

  • Maintains NURBS surfaces and part metadata.

  • Excellent compatibility with Revit, SolidWorks, Fusion 360, and more.

Cons:

  • Not suitable for high-poly meshes or animation.

  • File size can become large with complex assemblies.

  • Limited support in artistic tools like Blender.

Watertight Tip:

STEP files are typically solid bodies by definition. However, export settings matter—use BREP export and confirm that faces form a closed shell in your CAD software.

Bonus: How to Check if a Model is “Watertight”

Regardless of file format, watertightness means that your model has:

  • No open edges or holes.

  • Proper face orientation (normals facing outward).

  • All meshes merged and non-manifold edges removed.

Tools for watertight checks:

  • Blender: Enable the “3D Print Toolbox” and use “Check All”.

  • Netfabb: Offers automated mesh repair and gap detection.

  • Rhino: Use “Check” or “ShowEdges” to find naked edges.

  • Revit: Though not mesh-based, exporting solids with proper BREP options can ensure closed geometry.

Final Thoughts

Choosing between STL, OBJ, FBX, and STEP isn’t just about file compatibility—it’s about aligning your end-use intent with the strengths of each format. Whether you're exporting for fabrication, rendering, animation, or coordination, the correct format—and a watertight mesh—will save you hours of frustration.

Semantically aligned exports not only enhance downstream workflows but also future-proof your assets for interoperability and reuse. And in a world where digital assets flow between industries, exporting clean, watertight, and well-structured models is a skill worth mastering.

Michelle Greeff