Repair an STL File
Weld duplicate vertices, remove degenerate triangles, recompute normals and get a report of open and non-manifold edges before you slice. Basic repair for common export problems.
How it works
- 1Drop the file
Open edges and non-manifold edges are counted immediately.
- 2Repair
Duplicate vertices are welded, zero-area triangles removed, normals recomputed and flipped if the mesh is inside out.
- 3Review the report
If open edges remain the mesh has real holes; the slicer's repair or a tool like Meshmixer is needed.
Details
Most "broken STL" problems are small: vertices that should be shared but are stored twice, triangles with zero area from a bad export, or normals pointing inward. These make slicers report errors even though the shape is fine. This tool fixes exactly those problems deterministically.
What it does not do is fill holes or resolve self-intersections. The report tells you how many open edges remain so you know whether the slicer's automatic repair (which most modern slicers have) will be enough.
Accepted formats: STL, OBJ, 3MF, PLY
Frequently asked questions
More STL tools
- Get the Dimensions of an STL File
Drop an STL (or any 3D file) to read its exact width, depth and height, bounding box, volume, surface area and triangle count. Runs in your browser, nothing is uploaded.
- Reduce STL File Size (Simplify Mesh)
Cut the triangle count of an STL file by a chosen percentage while keeping the shape. Useful for oversized 3D scans, slow slicers and upload limits. Runs locally in your browser.
- Convert STL ASCII to Binary (and back)
Convert a text (ASCII) STL into the compact binary STL that slicers load faster, or the other way round for inspection. Binary files are typically 4–5× smaller.
- Scale / Resize an STL File
Resize a 3D model by a factor, to an exact target dimension, or fix a model that came out 25.4× too small or too big because of inch/millimeter confusion.
- STL File Info: Binary or ASCII, Triangle Count, Header
Inspect what is inside an STL file: encoding, header text, triangle count, bounding box and whether the mesh is closed. Handy before sending a file to a print service.