Repair Mesh Normals Online
Upload your mesh to Paramesh AI's free cleaner at parameshai.com/clean. It automatically detects and fixes inconsistent face normals, ensuring all faces point outward. Works with STL, OBJ, PLY, and 3MF files. No signup needed.
What are mesh normals?
Every triangle face in a mesh has a normal vector indicating which direction it faces — outward or inward. When normals are inconsistent (some faces point in, others out), the mesh appears inside-out in renderers, fails boolean operations, and can't be 3D printed.
Why normals break
- Boolean operations in some CAD tools flip normals on the cut faces
- STL export from certain software doesn't guarantee consistent winding
- Manual mesh editing can accidentally invert faces
- Merging multiple meshes without checking orientation
Automatic repair
The Paramesh AI cleaner uses trimesh's fix_normals() which propagates consistent winding order across the entire mesh. It's equivalent to "Recalculate Normals" in Blender but runs in your browser with no software install.